Not being bombarded by advertising will save your bandwidth and as a consequence will improve your browser speed and page load speed.
It will also save you irritating advertising sessions interrupting your videos.
How to block YouTube ads
The best way to block YouTube ads is to install an ad blocker add-on on your Firefox brower.
You can find Firefox add-on here: https://addons.mozilla.org.
Best Youtube Ad blockers
uBlock is free, open source and easy with CPU and memory efficiency. It blocks Youtube ads.
AdBlocker is free and open source. It blocks 100% of ads and is guaranteed without any whitelist.It blocks Youtube ads.
AdGuard is free and open source. It blocks Youtube ads.