For the file selection issue, I actually already fixed that, it wasn't working for any file types before after uploading, I'm not sure why it would be any different for .flv but I'll look into it.
As far as the mime types for files like webm I added stuff to Web.config in the system.webServer section for that but it may only apply when using IIS rather than the VS web server. Are you using the latest web.config from the repository?
Another possible factor about the full screen could be if you are not using the same Web.config as me (ie the latest copy from the repository) then you may be using a different version of jQuery. Worth a try eliminating that as a possibility, I'm using the very latest version. The version is configured in Web.config.
Hope that helps,