The new versions of the Chrome and Firefox web browsers include support for a relatively new video codec called AV1. This codec has features that surpass all the other available codecs. And now YouTube supports this new codec too. As of now you can use only Chrome and Firefox web browsers (also other web browsers based on these two) for making use of this new AV1 codec.
AV1 is a new royalty free video codec that is available in all the modern web browsers such as Chrome and Firefox. AV1 is slowly going to replace the aging H264 codec that is prevalent on the internet today. The benefits of AV1 codec are higher compression level and better quality at the same time. It can compress videos 20% times more compared to VP9 codec and 50% times more than AVC codec.
With such a higher compression rate, you can now get more video at reduced data transfer, which means, a smaller video file can contain high definition video of long duration. Using the AV1 codec you can enjoy HD video streaming while spending very small amount of internet bandwidth.
In your Chrome or Firefox web browser, you can visit https://www.youtube.com/testtube and then you will find the AV1 codec available there. If it shows that AV1 is not available for your web browser, then you should first update your web browser to the latest available version. AV1 is set to auto mode by default in the YouTube test tube, but you can set it to be selected automatically for the SD videos or you can set it to be used automatically for both SD and HD videos.
According to YouTube, for using AV1 codec you need a very powerful computer with good GPU. This is because the data decoding has to happen very fast and it may fail to work properly on low end computers.