That I am ware of, all current VJ apps that run on Mac OS X use QuickTime 7.x. The primary reason for this is that QuickTime X does not currently have all of the functionality that 7.x possess. From what has been explained to me by David (and David, feel free to correct me if I am wrong) Apples current roadmap does not indicate that they are planning on re-implementing much of this old functionality into the new version.
What this means is that for the future we may likely have to find an alternative solution to video playback.
@vjspetto, thank you for your report. My experiences in the field have been similar and I agree with your points about what needs to be added. In regards to the texture limit, there is indeed a limit that is dependent on the card. Around 8000 x 8000 pixels for some cards. Others allow a bit more.