A JPEG-DVD is a DVD-disc with JPEG-files burned as a regular data-DVD.
To try out the JPEG-DVD compatibility of the EuroLine 6642M, I burned a DVD with the same structure as the CD I burned to test JPEG-compatibiliy. Then I inserted it in the DVD-player and hoped for the best.
To my surprise, the 6642M had no problems with this disc! It displayed the JPEG pictures and everything behaved exactly as in the JPEG-compatibiliy tests!