This is probably the biggest site that concentrates exclusively on movies that are created on an emulator. Games completed on the real console don't produce a movie file.
I know Doomworld produces also the movie files of their records (in fact, they only publish those, and not AVIs). If you are interested in Doom speedruns, check
http://www.doomworld.com/tas/.
TAS-making is also known in Japan (under the term "timeattack", タイムアタック), but they are generally found in rather closed communities with no contact to foreign countries.
One such site is
http://www.geocities.co.jp/Playtown-Denei/3370/entry.htm. Naturally, it is in Japanese language. (You need to select SJIS encoding manually because it's a designed-for-Microsoft-IE-with-Japanese-defaults page.)
Then there are plenty of individual publishers who only publish their own movies. Many of their productions are also found on this site. Your best bet is to use a search engine such as
http://www.google.com/.