Here's what I see when running DAIN-APP 0.42A with video as input:

Starting PNG frames extraction!
Finished PNG frames extraction!
Starting Interpolation!
  0%|                                                 | 0/30364 [00:00<?, ?it/s]

I'm using the default settings except for enabling:

• Don't interpolate scene changes
• Create a output with audio

It could be because of the "Don't interpolate scene changes", this build is pretty broken. Can you try without this option? But still advice against using 0.42

I've confirmed the following with 0.43:

At first I thought 0.43 had the same issue with interpolation not starting. GRisk, you were right that when I uncheck "Don't interpolate scene changes", everything starts normally.

Then, I realized that "Don't interpolate scene changes" actually does work if I wait long enough. With that setting enabled, it took hours after PNG frame extraction completed before interpolation started. With "Don't interpolate scene changes" disabled, interpolation starts immediately.