I had the error "video codec not supported" trying to view video's using the wireless option on my samsung tv or my samsung bluray player, but once I added encoding to the video's having this error using Microsoft Expression Encoder 4 (free version) http://www.microsoft.com/expression/products/Encoder4_Overview.aspx
it fixed this issue.
So, using allshare or DNLA wirless streaming video, what some files are missing is the correct encoding! I was able to do this to .wmv, avi and mov files. Either seperately or making a windows live movie maker wmv file and encoding that final result. Why no one has this info posted anywhere I looked (and I looked high and low) I have no idea, but yeah theres the fix..