I would like to see in-depth videos on programming synths. You can find a lot of the basic stuff on the Net (mostly centered around subtractive synthesis) but videos that REALLY explain tips and tricks about programming synths like Massive would be great.
Also, synths like FM8, Alchemy and Absynth are powerhouses in their own right. A good video showcasing their possibilities would be nice as well: how to program an FM synth like the FM8, what bizarre options are their with Alchemy etc. :)