davidd provided me with the Sony demo. Here are my findings:
1. The file is really a Program Stream file, not a ts, as the extension says. At least that is what Cascade reports.
2. There are a couple of glitches in the file. About 3 in the first 3 minutes. They are tiny video jumps, like a frame or two are missing.
3. The file is very close to 25 Mbps.
4. The file plays fine with MPlay with my setup (WinXP, smb, wired eth)
5. Probably because file fragmentation, timing the copy of the file to /dev/null gives me 25Mbps.
6. I can play the file many times without it stuttering.
Once, during playback the image paused for a fraction of a sec and audio was lost. Considering that I'm at the limit of how fast the server can serve the file, I'm not surprised.
So, please check the network speed for streaming this specific file:
time cp sony1080i.ts /dev/null
Take the size of the file, multiply by 8 and divide by the number printed as "real", in seconds. If the result is less than 25000000, you have a server or network problem that prevents you from playing this file.