YouTube a few days ago released a new Video Quality option of 144p. Instead of the lowest quality being 240p, you can now view a select few videos at an even lower quality.
The reason for this was not officially announced by YouTube or Google as of yet, but it is fairly easy to assume that they wanted Mobile users and users with slow internet connections to be able to buffer videos faster. Along with mobile users, some ISP’s limit YouTube’s bandwidth causing buffering to take what seems like forever.
Currently the 144p option is available on a few select videos and channels. I have noticed this option on popular channels only having over 100-thousand Subscribers. YouTube may have the setting on videos that get a large number of mobile views, or on general video view counts. As mentioned before, YouTube did not make any official announcement yet, so you may not see this option on your channel for quite some time, if ever.
One issue I have noticed with 144p is the lack of sound. It appears that they removed the audio from the quality 144p and only have video. I personally would like an option to pick between Audio and Video in case I wanted to listen to music through YouTube on a mobile device with low bandwidth I could.
As YouTube stands now, the available quality options are as follows, 144p, 240p, 360p, 480p, 720p, 1080p, and 4k.