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!