So by now we are all used to just uploading whatever we want to YouTube and letting the site do it's thing. Unfortunately, this is not the case for most unincorporated video sites. So, if you want everything to go smoothly, encode your videos @ 640x360 and then upload them. Otherwise, they may seem stretched or scrunched. Click the link below for some more information.
You can now even directly embed your existing YouTube videos to your own channel. You may upload files of any length and up to 1GB in file size.