VLC on Slackware 12.1
Some time ago I had a lot of problems viewing some H.264 or x264 files. Apparently, my favorite video player, mplayer does not support the complete H264 specification, so it has problems with some of the files out there (reads in the length wrong so you cannot move to, say, middle of the file; audio and video goes out of sync, etc.)
So I turned to other solutions. Xine fall flat on face as well, and although ffmpeg plays it fine it doesn't have fast forward/rewind and fullscreen option that is actually usable.
The thing that worked out is VLC, which I first had to confirm on Windows, since it was much easier to set it up there. Making it work properly on Slackware was not easy. After having problems with prebuilt packages, I decided to roll my own.
I do a lot of wxWidgets development myself, so I used an already built wx version 2.8.7. VLC compiled, but crashed at startup (I got segmentation fault with vlc, wxvlc or svlc). I looked at the website, and it says wx 2.6.3. That one is buggy unless you patch it (patch is at wx website), so I first tried with 'safe' 2.6.2 which has proven to be rock solid in the past. However, 2.6.2 doesn't compile with Slack 12.1's default GCC 4.2.3, so I went for wx 2.6.4, which turned out to be a right choice. Just make sure you build wx in release (not debug) mode, as there are some problems with wxLog functions and VLC.
Here are the relevant versions that are compatible:
Slackware 12.1 (with various media codec for 11.0 and 12.0 installed from linuxpackages.net)
VLC 0.8.6f (--prefix=/usr)
wxWidgets 2.6.4 (--enable-unicode --disable-debug --disable-shared --prefix=/usr)