Wait.. the phone actually uses vibration motors while playing audio? I thought it was just reverberating inside the device. If so, that seems like a waste of battery life.if this rom has the vibration feature in the back of the phone while playing a video/music like the stock rom's one.
Edit: Confirmed. It's just reverb inside the device caused by the speaker in the ear piece. If you go to accessibility and enable "Mono audio" and then move the audio balance all the way to the right, the audio will exit the bottom speaker only while maintaining both L/R channels, thereby fixing the "issue". On the other hand, if you move audio balance to the right without enabling mono audio, you'll completely lose the sounds you'd normally hear from the left channel. In the end, this isn't a "feature" included in a rom, but a result of the actual hardware and physical design of the device.