This solution will solve your problem of stuttering playback when downloading HLS streams.
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1. Enable HLS as m2ts under behaviour in settings and then
2. run the command 'ffmpg -i name.m2ts -c copy name.mp4' on the downloaded video to remove the corrupted data causing the stuttering.

I wish I could take credit for this solution but I cant. I found this solution on a videodownloadhelper q&a google group forum.
the user marcel posted this solution so without further ado here's the link to that forum: https://groups.google.com/g/video-downloadhelper-q-and-a/c/Gmbmr1ZMKwY

Need to process a batch of corrupted HLS Downloads?

A user posted a nice powershell script at the bottom of the forum. Its speeds up the process when doing a batch of hls downloads.

From what I read on that forum the hls stream issue hasn't been addressed yet due to licensing issues but they plan to fix this problem in a future release once its not a licensing issue.

Thanks marcel and Sergey Sivushkin for originally posting the ffmpeg command and the powershell script.
i couldn't figure it out and it was driving me nuts to have to re encode every hls download.

Download is working correct now.

Nice Add-on. But Latest Version has no function "2K/4K" Youtube video saving.

概ね良好です。まだ広告をダウンロードしてしまう時は有る。

Do its job but the UI is awful