Extend video clip in Davinci Resolve that has been slowed down/paused
If you use Retime Speed instead of Retime Frame, the clip can be extended.  Retime Frame gives you the ability to arbitrarily access the source media according to the curve, but there's no concept of time stretching--the clip in the timeline has a fixed amount of time and the only variable is what frame to play at a given time.  Retime Speed controls the concept of time.  If you slow the speed down to 50%, you get 100% more time for your clip to play.  When you slow the speed down to 0%, you get infinite time to play your clip (and interesting edge conditions--so keep it to something like 1%).