The touch bar using lots of power? No way. Sorry. Just not possible. First of all, it's on OLED display. Only the pixels needed to display. LCD's require back lighting which consumes more power. The processor running the touch bar is running WatchOS which also doesn't use much power.
Notice how your touch bar goes dark after not using it, or typing after a while? No power used. I believe the processor also goes in to standby, consuming even less power.
Quite frankly, I'm shocked at how long my 2017 15" MBP lasts on battery. Getting 10+ hours on a machine of this calibre is amazing to me.
I'm able to use the touch bar to change the volume of anything playing, including YouTube. Not sure why the OP is having an issue there.