MKVs do have thumbnails using Sharks package.
just make sure that DivX MKV Splitter is enabled in the MKV tab.
If you have Win7 x64, you need to have the 64bit addon and have it enabled there.
I think MeGUI or Handbrake are the best 2 choices for encoding, and are free.
Like I was saying before, since Shark's pack depends on DivX to do all it's cool MKV stuff and Windows 7 has native Media Foundation drivers to do everything but AC3 (actually it does AC3 too but licensing prevents it from being used with MKV) why install a ton of other junk when all you want is a native Media Foundation splitter (64-bit too!) and an AC3 filter with native ACM wrapper?
Good Questions and good points.
I obviously can not speak for everyone, but I can share my thoughts.
I do alot of video encoding. So in my case, FFD Show decoders is a must at times. The fact i can enable them or disable them is nice as well.
However, I find FFDShow to have superior picture quality, so i use it as my default decoder. Just my opinion there.
As far as DIVX goes, it does do well. I can't really say much bad about it, but it does have its flaws.
1. You need DIVX Plus codecs in order to play in external players. (IE WMP or WMC) This is a trial thing that you must purchase later.
You will also need AC3 filter to get AC3 playback in 3rd party players.
2. If you have HD videos in a MP4 container that contain AC3 audio, they will play video only. Even in WMP.
The DIVX Splitter doesnt seem to like them.
3. DIVX itself can sometimes have issues playing back certain AC3 files. Not sure why.
I do agree, that all that is in Sharks pack is not needed (at least for me). You will get no argument from there. But I only install what I need.
FFDShow, Haali, Gabest, AC3, DIVX foundation.
This way MKV thumbs work, and most any video plays in WMP and WMC without issue. And, theres no need to purchase anything extra later down the line.
And, I can still encode videos using FFDShow :)
Thats my reasoning at least. And of course, it will not apply to everyone.