I have an MP4 file of a movie and a corresponding SRT file for subtitles. As I've done before, I used the software Convert X to DVD to turn those files into a DVD that can be watched. The MP4 had been ripped from a Blu Ray disk (and maybe the SRT file too -- not sure). I played the DVD I burned on our Blu Ray player and high end high-def TV. It looked great until about 16 minutes into the movie when a message flashed up on the screen saying "unauthorized playback on this device, disabling sound" or something to that effect. We ejected the disk and tried playing it again, only to immediately get that same message. So I put the MP4 onto a thumb drive and played the movie in the Blu Ray player that way. I didn't really need the subtitles from the SRT file because the movie's in English anyway. We were able to play the movie just fine from the thumb drive. Also, the DVD that prompted that message played just fine on older equipment. I played it on a DVD player and a really old TV and never got the message. Are Blu Ray players (or TVs) now coming with copy protection technology that can detect an MP4 file that was ripped from a Blu Ray disk (or even a DVD)? I've never heard of a ripped video file still containing any copy protection. I thought once it's ripped all copy protection is stripped away. What about other file formats such as AVI and MKV? (I was actually surprised it was an MP4 from a Blu Ray disk and not an MKV -- I hear MKV is the way to go). If anyone knows the lowdown on the latest copy protection crap for Blu Rays and DVDs, I would appreciate any info. And why did the copy protection only work on the burned DVD and not when I played the MP4 directly?