Poor video performance in VB Linux guests since the last update(19.1.21)

since the last update both of my XFCE guests have both choppy stuttering videos playback in YouTube and on other sites.(it stops for a sec and resumes,or stops and then resumes while playing the same sound/image a few times etc.)
it’s not a buffering issue since the play bar is loaded quit beyond this point.

i thought I’d check the guest additions version and saw it doesn’t match the VB version.
I’m not sure if updating it is the solution,since when i first installed VB i didn’t explicitly installed it under “optional dependencies”, nor in the virtual machines,but apparently it’s there,so i thought I’d give it a try for the lack of a better solution.

my question is how should i go about it;
directly from the guest VM?(it already downloaded it to /.config/VirtualBox/ (but i didn’t install it yet),
or through pamac under VB in dependencies/optional dependencies: virtualbox-guest-iso:guest additions CD image"?

if you experience the same and /or have a better solution please let me know.
i could try enabling 3D acceleration or try another Graphic controller,but i didn’t have to resort to any of this before the latest update.