I (19M) deal with the same thing, I think for me it comes from not wanting to witness someone who is struggling get laughed at or "embarrassed". I was actually just thinking about this today, I've watched plenty of videos of others who stutter, but the thing that I also do is imagine myself in an audience with them being on stage being watched by me and a bunch of other people. The feeling is more so feeling anxious for them rather than it being about me. I would just say force yourself to sit through videos of people going through hard blocks and imagine it being a one on one conversation between the two. You understand what they're going through, hope this helps!