I would like to help try to place the use of the Botafumeiro in a liturgical and practical context. Within this context, most of the comments made above can be better understood. All of the above comments have value, even if I disagree with them. Remember, in life, context is everything...
In the Catholic liturgy, the use of censers has traditionally been to bless the altar, church, congregants, and celebrants (priests, deacons) BEFORE and DURING the Holy Mass. The use of a censer AFTER the actual liturgy is usually reserved for funerals, when the coffin / casket may be incensed a final time, blessing it before it leaves the church. Being raised in the Latin church - pre-Vatican II - I seem to recall the censer also being used at the end of some high Masses and Weddings. But I could be wrong. I served at altar as a young boy and seem to recall spooning incense into the much smaller censer at the Latin-rite Masses (1960s).
So, in Santiago de Compostela, we have I suspect the contemporary use of the huge censer (the Botafumeiro) outside it's normal historical context. I would suggest that, back in the day (Middle Ages) the censer was likely used at the beginning of the Mass to bless the altar, the celebrants and the congregants, and perhaps during the Mass, such as just before the reading of the Gospel and before the Eucharistic / Communion Rite - slightly after the Our Father is recited.
As has been oft stated here and elsewhere, the historical context also suggests that the type of incense used in the Botafumeiro and the volume of incensed smoke were in part intended to mask the smells of hoards of unwashed pilgrims. Trust me, there are various types of incense that can be used at different liturgical season of the year. I believe from observation and experience that the type used in the Botafumeiro in the Santiago Cathedral is a far milder mixture than could be used. If you doubt this, just ask a practicing Eastern Rite Orthodox Christian (Greek, Russian, Armenian, etc.). In this regard, I suspect a milder scented blend is used in case someone out there is allergic to the incense. There is such an allergy. Please correct me on this if I misstated.
Thus, I suggest that the use of the Botafumeiro at the end of the Mass, after the final blessing, is a calculated move on the part of the Archbishop to do a number of things - primary of which is to maintain some semblance of order, respect, and silence. In the film "The Way," the editing makes the Botafumeiro ceremony appear to be somewhere in the middle of the Mass. This is misleading. Also, I believe the fellows pulling on the rope harness are lay persons (not Monks) and are members of a Cathedral society devoted to the care, feeding, and swinging of the Botafiumeiro.
However, given the behavior of many people, of all backgrounds, nationalities, races, religious persuasion, philosophies, etc., certainly including many Catholics, when the Botafumeiro is used, an informed decision appears to have been made to move the Botafumeiro ceremony to the recessional, after the end of the Mass. Those of you who have attended the Pilgrim Mass and other Masses at the Cathedral can confirm that the Botafumeiro does not move until AFTER the final blessing is said and the celebrant (priest) dismisses the congregation..."...Go in Peace the Mass is ended..." Thus, and albeit technically, the Botafumeiro is no longer a formal part of the Liturgy.
If I am correct then the context for the Botafumeiro ceremony is therefore changed (technically) from liturgical to historical. I saw the ceremony to be part of the recessional music played at so many religious services of various faiths.
I can certainly understand the displeasure of anyone who thinks applause is disrespectful. I share this feeling. But I offer two perspectives. First, I have been at many weddings, in the U.S. and in Europe, Christian, non-Christian and secular, where the congregation applauds the newly married couple after the ceremony or Mass, when they turn from facing the celebrant to facing the assembled persons, before they process out of the wedding place.
Secondly, and I think this is the entire point of my "homily" here, the
Camino de Santiago, with the Pilgrim Mass, and the Botafumeiro has moved beyond being exclusively a Roman Catholic enterprise (if you will) to an ecumenical service. Once the United Nations (UNESCO) acknowledged and proclaimed the
Camino Frances and Santiago de Compostela to be World Heritage Sites, the entire context for the Botafumeiro ceremony changed. Originally and for over one thousand years, solely a Roman Catholic pilgrimage, now the Camino, Cathedral and attendant ceremonies should be seen in their expanded cultural, historical, archaeological, and political contexts.
So, and in conclusion (whew), if you look at the Botafumeiro ceremony in the expanded context of history, archaeology, politics, and religion, one can understand why the Botofumeiro ceremony was moved outside the actual Holy Mass. This was likely done because of the wide cultural appeal and the public attention, respect, silence, or lack of same.
Simply put, I believe they moved the ceremony to after the Mass and outside the Catholic liturgy to: (1) preserve the dignity and sanctity of the Liturgy; (2) maintain control of a diverse and mostly uncontrollable group of attendees (If they did it earlier, control of the Mass would be lost for good); and (3) to maintain the Botafumeiro ceremony as a regular demonstration of a precious historical and cultural practice.
So, if you only want to see the Botafumeiro, come later. If you do attend the entire Catholic Mass and stay for he demonstration of the Botafumeiro ceremony, please remain as silent as possible and be as respectful as the situation dictates. Obviously, if 95 percent of the pope three are trying to get photos, you might as well join in. But, please know that the Mass is over... Take your photos or video QUIETLY. Never mind the others.
I hope this helps. I tried not to repeat the comments above, and to add some value to the dialog.