Posting preview thumbs from clips would be a really welcome addition, especially to large split files. Realistically speaking, it is rarely feasible: the reasons why have been already explained.
But...
I'd like to submit a couple of links.
These are for the technical savvy: they are media utilities that replicate most of the official programs' funtionalities minus the limitations.
->
http://sourceforge.net/project/showfiles.php?group_id=82303
->
http://sourceforge.net/project/showfiles.php?group_id=82303&package_id=84358
I would recommend
Media Player Classic.
It does require some brainpower and time to the prospective user, but, so far, worked for me as a decent substitute to WMP and Winamp [for videos].
It also features
multistandard play - it can open Realmedia, Quick Time Movies, Dvix and Xvid, Windows Media Files, Mpegs - and nearly everthing you have installed codecs for.
It isn't flawless, and it seems
buggy with RM files - no big surprise - but just being able to open them outside RealPlayer is a big bonus.
Plus, it
CAN save individual frames from most supported formats.
Just be sure to download the right version: XP vs 98/ME.
It
doesn't require installation either, just be sure to know how to reset file association if you are not satisfied with it.
You can also draw and drop files on the players, without disrupting existing file associations.
I hope it works for you. For me, so far it's worked reasonably well.
Reg's.