Thomas Grove Carter, the video editor whose review of the MacBook Pro was highlighted in this previous post, tweeted this animated GIF showing off the Touch Bar sliders interacting with Final Cut Pro X.
The video first shows a volume slider, so make sure your sound is on. The second half shows the insertion of key frames in a video sequence. As you watch that part, keep in mind that his left hand is on the track pad, moving the mouse cursor, while he uses his right hand on the Touch Bar slider to adjust the key frame.
As Carter said in his review, the whole interaction is “buttery smooth”.