I have a fast internet connection, but have regular buffering problems on various movie streaming sites (some sites worse than others), even in the latest Firefox 146. Tried all the about:config tweaks, disabling extensions, etc etc. but nothing worked. The problem was instantly resolved with this extension. It also instantly resolved a persistent audio sync problem, even in netflix. Lip sync is absolutely perfect now. Can't get it to work properly on youtube, or at least its buggy, and I couldn't be bothered figuring out why, because i never have problems streaming youtube videos, even at ridiculous speeds (I use youtube enhancer).
One recommendation: by default, fastStream is set to "predownload the entire video in the background if possible". I think this is overkill, the extension works so well, you can easily turn this option off, with this option off it preloads movies about 4-5 minutes ahead, which is more than enough.

I love this addon, it's truly cream of the crop. I have iffy internet, I love the peace of mind knowing that I will be able to finish a video if I experience an outage.

There are also many other features that I've gotten lots of use out of, and the customizable hotkeys have made it easy to use.

Does not work for youtube anymore, need for fix update!

Wow... I normally don't write reviews, but this addon blows my mind. I was already happy with the streaming boost it delivers on every streaming site. But then I pressed the audio button... What the hell, a completely free, working equalizer.... Damn this thing delivers!

Fantastic addon for when you have problematic Wi-Fi!

You can't watch the series yet, except for the first episode. I'm sorry my very bad English

Youtube keeps breaking it, but it's not the extension's fault. Still annoying, but works very well when it's fixed.

It's been quite comfortable to use. However, there are quite a few times when it fails to load videos initially and requires several reloads before starting. If it doesn't play, adding a feature like automatic reloading would make it even more comfortable.

Warning. After having issues with the player filed a bug report. I did this as I wanted to aid the developer with fixing issues with the player as it is a free addon. However after jumping through hoops to assist Andrew, I have come to the conclusion that he is very incompetent, and lacking. This does not bode well for FastStream.

It doesn't work with the addon Firefox Multi-Account Containers, the player loads underneath the default Youtube player.

So far so good, my only real complaint is that it doesn't work well with another extension: Sponsorblock

It's Worked on every site, and Increased video optimization and Browser player. Big Like

It works as advertised. The videos I've been trying to watch buffered endlessly, but not anymore.

Seems very fast. Needs an option to deactivate ALL KEYBOARDS and set the preload per file.

Fantastic and versatile extension!! I installed it mainly so I could continue watching videos while moving in/out of areas with slower wifi connection around my house. Not only has it worked perfectly for this purpose, it also offers an awesome array of accessibility features and customization options which anyone could benefit from. Highly recommend