Made a mistake! The crash reasons actually stated are: EXC_BAD_ACCESS / KERN_PROTECTION_FAILURE EXC_BAD_ACCESS / EXC_I386_GPFLT EXC_BAD_ACCESS / KERN_INVALID_ADDRESS although before I reinstalled they were all EXC_BAD_ACCESS / KERN_INVALID_ADDRESS

You can try to disable hardware acceleration in Firefox.

• Options/Preferences -> General: Performance
  remove checkmark: [ ] "Use recommended performance settings"
  remove checkmark: [ ] "Use hardware acceleration when available"
• https://support.mozilla.org/en-US/kb/performance-settings

Close and restart Firefox after modifying the setting to make changes effective.

• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can check if there is an update for your graphics display driver and check for hardware acceleration related issues.

• https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration

Just tried it. It stopped crashing for a minute and then it crashed again with the same crash reason. I can't update my macbook because it is outdated and unable to update to the latest version.

I am not using Windows 10, not Linux, and not Mac OS either. My system is older also. I haven't had any Firefox crashing on YouTube. However, when I play 1080p60 videos with the codec avc1.64002a(299), basically codec "avc", it causes my older video card to use the "Video Engine" instead of the GPU. You can see this in TechPowerUp GPU-Z. "Video Engine" goes to 88% and causes my mouse to respond slower/sluggish. I do not get any crashes though. If you want to obtain information regarding the YouTube video you are playing, right-click on the video and choose "Stats for Nerds".

If I play a different 1080p60 video with the codec vp09, only the GPU is used at 11% and there is no effect at all on my mouse. I believe the "Video Engine" is software rendering and the "GPU" is hardware rendering. That's my estimate. 1. 1080p60 videos with the codec avc1: https://www.youtube.com/watch?v=nz6F8eNbk1A 2. 1080p60 video with the codec vp09: https://www.youtube.com/watch?v=AA_rZZbVAWQ

Perhaps you are getting crashes on certain YouTube pages because you are attempting to play 1080p60 videos encoded with the "avc" codec. Otherwise, it could be the YouTube pages have become much more complex.

You would need to give more information such as your system specs: CPU, RAM, etc... Also, you would need to tell us the specific pages your Mac crashes on.

Here are the specs of my macbook: CPU: 2.3 GHz Intel Core i5 GPU: Intel HD Graphics 3000 512 MB RAM: 8 GB 1600 MHz DDR3

The codec avc video you linked played just fine on 1080p60 with no slowdown but this video (also uses codec avc) makes Firefox crash instantly before the video even plays. Firefox also instantly crashes when I go on certain Discord text channels. This only seems to be happening on YouTube and Discord pages and I am discovering more and more pages that cause the crash every day.

Safari doesn't crash on the video linked above but it does on the discord text channels.

I just tested the video linked in my previous reply and Discord again.

Both the video and Discord run normally for a few minutes after relaunch but then causes the whole browser to crash suddenly, but after the crash, both sites instantly crash upon entering.

hmm, that's weird. Crashes no longer seem to be happening. I will update here if it happens again. If it stops crashing for more than one week, I will set this reply as the solution.

The same crashes are happening again after I switched hardware acceleration on and off when all videos were eternally loading (fixed) so I am suspecting that it is caused by a bug somewhere in hardware acceleration settings.

.....

mozilla did not post my comment for you. It was very detailed. It would be best if I just private messaged it to you. I don't know why mozilla did not post my comment. I probably will not be posting any more attempts at solutions here. Private message me and I'll send it to you.