Is this a change in the last month or so from the earlier nightlies? That's part of why I spent so much time on this. I'd swear that the re-encoded videos used to be "vda-h264", then a month or so ago I noticed that they no longer were. Eventually I became convinced it was an encoding error.
Is there a discussion somewhere about why this was disabled for SD content? I'd love to read up on the rationale.
At first, anything was h.264 was allowed. Then I re-read the Adobe blog about their experience with VDA decoder and h.264. They don't use VDA for SD content because it's a push in CPU usage.
Then I thought long and hard about what containers have h.264 inside that is SD sized. The result was Xvid and AVI's. Now I really hate AVI's not because it's a crappy container format but because AVI's always seem to be encoded with the most brain dead encoders around with wacky DTS and PTS. Now with VDA decoder, I can only pass one through, that really needs to be PTS in case PTS needs to be re-ordered with does happen with h.264.
Add the above to the fact that VDA decoder is only available on boxes that can run 10.6.3+ AND have nvidia chipsets. Those are all 2.xGHz+ Core2Duo boxes which can easily handle SD h.264 decode with ffmpeg.
Then I disabled SD video content from VDA decoder usage. It was an easy choice.