Is there a way to make long videos play more smoothly?

If its only 4 minutes long, then Storyline shouldnt really have any problems playing something like this, and I've found the ADAPTIVE setting to be quite good.

I suspect the problem lies within the video file itself and how its been encoded.

Some things to check might be: (these are within the actual video file itself, not Storyline)
- is it using h264 codec for video
- is it using MPEG AAC codec for audio
- is the audio rate set to 48KHz
- is the video frame rate set to 24 fps
- is the resolution larger than the actual size in your Storyline slide

Thats where I would start to look.

One other thing to consider is I have noticed that a recent Windows update caused my Windows Media Player to play videos back with a stutter. Using any other media player (eg. VLC) or a different computer, my videos are perfect.

So maybe just verify that its not your actual computer by trying it on another computer or mobile device?

Hope it helps!

Thank you so much for your help Andrew. I will look into this : )