How long the URL of a YouTube video last before expiring?

On executing youtube-dl -g <youtube_link> we get the urls for the video and the audio, we can play those urls with vlc for example.

But for how long those urls are valid?, they’re of the form:

https://rr4---sn-uqx2-w50l.googlevideo.com/videoplayback?expire=1703633398&ei=lg2LZYr4Jv_6j-8P45iR-Ak... 

What’s the meaning of that expire=1703633398.