There are two pretty frustrating things about using a Media Center extender as your primary video solution (if using third-party applications and non-native video formats):
1. Third-party add-ins either get over or under scanned so there is a either a border around the edge of the screen or a portion of the video is drawn off the screen both look tacky.
2. Non-Native video formats like mpeg 2 do not get fast forward or rewind unless you have wrapped it in a native format (dvr-ms).
Well there are actually good reasons for these problems, for #1 each TV under scans a little differently so there is no way to have a perfect way to guess where to draw the third party code; now I do think they could mask this problem but I digress.
On #2, what they have done is made the decision that since they won’t be able to fast forward and rewind on 100% of this content they won’t do it for any of it; I personally wish they would choose to just try and not expose it in only the bad cases but these are the sorts of tradeoffs you make to make a product more predictable and supportable so I understand.
That brings us to the reason I was doing this post, you can work around both of these issues (sort of): see this thread on mymovies.name for more information: http://mymovies.name/mce/forum/Default.aspx?g=posts&t=1965