i've been wondering is there any way we can research how many a keyword is searched in youtube ? any software to do so ? or we just use standard wordtracker and overture ?
Try keyword tools and search for you tube and see what come up. Then figure out niche terms for type of videos.
You may try the Adwords keyword research tool on which you can search keywords in youtube. https://adwords.google.com/select/KeywordToolExternal