EDIT: may be better in its choice of frame, but here it's noticeably slower for MDBU (and thumb generation), plus you still need a codec pack if you want to preview your movies in XY (or in general, depending on your player). Media Preview - Shell Extensions: seems interesting! I'm curious to see how it compares to K-Lite. After some time with CCCP, I now happily use its 'Basic' pack. The most well known, comprehensive, and frequently updated, is probably ' K-Lite Codec pack' (free).
You can find finely tuned ones depending on your OS and tweaking needs, here for example.
