Next beta! This one brings a couple of bugfixes and improvements. This is also the last version before the first "actual" release where I've done major internal changes (unless I run into any major problems). Now, what's different?
The biggest difference is that I've done a major overhaul of the way the UI is drawn to the screen. Without going into too much detail: the way I was doing it before was neither clean nor efficient. It's much cleaner now and I can also start to speed up UI drawing (up until now I had to redraw the whole widget when something changed, now I can do it more efficiently, and I've started to use that in a few widgets).
Another big change is the way video is rendered, this is now done in its own dedicated thread and the GPU (using OpenGL). This results in video that is scaled and much smoother than before.

A note about video in boxen: I consider it to be a successful proof of concept. It needs more work to be truly useful, and that's why I will disable video playback in the next release of boxen. It will of course come back in the first 0.2-dev release.
What else? A couple of bugfixes, a new, updated version of libsndfile, which fixes issues with a lot of FLAC files. And I've started to work on boxen's metatag parser again, umlauts and special characters now work in mp3 metadata.
On that note: maybe you will notice the text "T: " and "A: " in the metadata display. This stands for "Title" and "Artist" and it will be gone in the next release, but it's part of a test I'm doing. I think it solves the mystery of the disappearing metadata display that has plagued boxen since its humble beginnings. If this workaround works (and it looks good so far) I'm pretty sure I have the solution for this problem. And please don't pay any attention to the fact that track names are broken in the browser tab - I know, it's not pretty, but it's a side effect of me messing around there. It'll be fixed in the next version.
And finally something audio related: gapless playback should work with a large number of mp3s now. However, I have not extensively tested this (since it's really, really hard to test if gapless playback actually works).
From the release notes:
15 July 2011: Version 0.1-beta1
[+] Included a copy of the LGPL license in the download bundle (libsndfile, ffmpeg and libcairo use the LGPL license)
[+] Video output is now done via OpenGL, which also handles resizing
[+] Implemented decoder support for multi-channel audio (output is currently still stereo, though)
[*] Fixed: A bug in the decoder would mark clips as "end of file" prematurely, this is the reason why a lot of videos would more or less randomly start to fast-forward to the end
[*] Fixed: Special characters in ID3 tags are now converted to UTF-8
[*] Fixed: An issue where the mouse cursor would stay visible after clicking on a knob control
[*] The video tab now automatically appears as soon as you play a video file
[*] Video rendering is now done in its own dedicated thread, video playback is generally much smoother
[*] Improved UI drawing performance
[*] Updated libsndfile
[*] Better gaplass playback (still not good enough)
[-] Temporarily removed support for VorbisComment (wasn't working properly anyway)
[-] Removed the option for the video tab
Download: boxen download page