I am not 100% positive but I believe you can only use the windows media player for files on your PC or attachments you have downloaded. I have not seen it used for any videos that are hosted by an outside source.
The Google Video is very easy to use and they offer the full screen option. They also have an option for uploading large/multiple videos quickly. I would say give them both a try and see which works best for you.
BTW - I learned to do all this stuff right here on this site!!
