My nVidia drivers wont update in Ubuntu 20.04.3. How can I fix this? (I will put the screenshot in the description)

I just installed Ubuntu 20.04.3 on a Dell XPS M1730. It works, its really good. But the problem is that whatever video I try to play (local or on the internet) it lags real hard.

I can hear the sound, but the video lags. My current nVidia driver is the 8800GTX. I thought the driver wasn't updated so I tried to update it. I keep getting this message:

If its not a driver problem, please let me know.

Also if you know why the video lags, please let me know (it's not the internet problem).

Supporting this question - since the OP tries to run his old hardware on a current Linux I'd like to mention that an old NVIDIA driver (which needs to be used by that hardware) does not necessarily work with the actual kernel. The question has been asked and answered here already and should be taken into consideration.

You need to remove the "modern" 5.11 kernel and install the 5.4 kernel in order to get it to work.