Use of nested scrollbars

Related to #26945 (closed)

During usability testing, a user commented that he disliked and struggled to use nested scrollbars. [Clip 1] (https://youtu.be/RQGV7y-6uoQ?t=14m16s) .

Generally, nested scrollbars do have a bad rep for usability.

As a team, how do we feel about this? Is there an alternative?