I have never bought bootleg movies/music, but for the sake of research, I borrowed a couple of concert DVDs that were bought in Shenzhen. Both are the same Hong Kong concert - Alan Tam/Hacken Lee 2003. And I compared them to the official set that I have. Here are the observations:

1. Picture Quality. Both bootleg copies are about equivalent to VCD quality, which is about half the horizontal resolution of DVD, and about the same as VHS.

2. Sound Quality. Both are crap. The DD 5.1 tracks are actually 2.0, with no signal in the other 4 channels. One set retains the DTS logo of the real thing, but when you choose "DTS" in the menu, nothing happens.

3. Compatibility. One set will play on about 3 of my 4 Region 1 NTSC DVD players. Another set only plays on one, if I remember correctly.

Conclusion - These aren't even copied from the DVD. Instead, the material is lifted out of the VCD releases, and burn onto DVD. I believe it's probably the same with many bootleg movies. Since you can buy the official VCDs in Hong Kong or elsewhere for only about US$3, I wouldn't even bother with getting the bootlegs to save US$2, and letting the bootleggers profit, and making yourself nervous/uneasy, and worry about the discs not playing.