One other thing: I have disabled all of my Add-ons/extensions and it seemed to fix the issue - but temporarily. As I turned each one back on individually I closed YT, closed FF, reopened both then selected a new YT video. It seemed to have a random effect - I thought I had figured out which extensions were the issue, but I tried it again to verify and got the same problem regardless which extensions were enabled/disabled.

I took a look at your addons & it could be the Disable Youtube Autoplay addon. But really its more likely its any kind of ad blocking addon you have because Youtube has gone full hardcore on blocking ANY kind of adblocking addon or tool you may be using. And will automatically skip a video you want to watch to the very end.

I don't think Grammarly or LastPass is breaking Youtube. But MalwareBytes Browser Guard & Web Threat Shield (from WebRoot) might be getting detected by Youtube as adblockers. Try disabling these 2 addons & testing Youtube for a longer period of time. If still seeing the videos playing super fast or skipping to the end, try disabling DuckDuckGo Privacy Essentials.

Please read this article for more info: https://www.ghacks.net/2024/05/30/youtube-is-automatically-skipping-videos-if-you-use-adblock-plus/

Thank you for the reply. I am taking your advice and will work with the various extensions on/off for a few days then come back here to let you know the results.

Here's how I resolved the issue of YouTube skipping to the end of videos instead of playing them normally. The extension Malwarebytes (MWB) has three components to it:

1. Ads/Trackers
2. Malware
3. Scams

You can turn any or all of them off for certain websites.

While on YouTube.com open the MWB extension manager (just click on the MWB icon at the top of FF and Chrome) and turn off Ads/Trackers and that resolved the issue.

All of these extensions seem to have no effect for me as I tested them through troubleshooting individually: DuckDuckGo Privacy Extension Facebook Container Grammarly LastPass Open Link with New Tab

It looks like you're using version Firefox 127.0.1. Please update before testing extensions.

I'm using 127.0.2 and FF has no update notifications for me.

Here's how I resolved the issue of YouTube skipping to the end of videos instead of playing them normally. The extension Malwarebytes (MWB) has three components to it:

1. Ads/Trackers
2. Malware
3. Scams

You can turn any or all of them off for certain websites.

While on YouTube.com open the MWB extension manager (just click on the MWB icon at the top of FF and Chrome) and turn off Ads/Trackers and that resolved the issue.

All of these extensions seem to have no effect for me as I tested them through troubleshooting individually: DuckDuckGo Privacy Extension Facebook Container Grammarly LastPass Open Link with New Tab

Awesome work StopTheInsanity! Glad you were able to track it down to MalwareBytes Browser Guard. Youtube has gotten very aggressive about blocking anything that blocks its ads.