The weepiness you describe, I think I can relate... I have found some videos, usually of festival/concert crowds, that give me a similar feeling. The "togetherness" gives me a specific kind of goosebumps... on my cheeks. There is a subreddit called /r/HappyCrowds that gathers videos of such moments and I think I am addicted. Here are some of my favorites: The first one is of 1000 italian Foo Fighters fans playing one of their famous songs as a way to convince the Foo Fighters to visit Italy :) The way the drummers are playing in synchrony :) The second one is of a Haka flashmob. Haka is an ancient Maori war cry/dance. The third is probably the one that comes closest to what you mentioned. A massive choir of multiple thousand singers performing a traditional latvian folk song. There is more if that interests you :)
I get weepy listening to and watching the Wikipedia edits: