Well, you're asking for two different things, now. You want to (A) display a single video in a single post and, (B) a page that displays multiple videos (a gallery).
You can keep the gallery as-is, if you're happy with how that looks. But you would have to create new categories with the individual videos to display single videos in a post.
I know it doesn't sound very efficient, but MyVideoGall is designed to be a gallery (Gall), so you have to present your videos in galleries, even if it's just a gallery of one.
You may want to search for a plug-in that allows you to "tag" videos with something that could be filtered on - or even something that allows multiple tags, but I'm not aware of MyVideoGall having that capability.