Issues with sound when playing video clips from a powerpoint

[JulieH1]

Having terrible issues playing video clips in a meeting from a powerpoint - this is a recent occurrence (today!) have never had an issue before with the same clips - loud hissing noise which is only cleared by turning the mic on and off - cannot play the clip all the way through without the issue happening

[pwright]

I am also having an issue playing videos that are part of my presentation, although I have clicked the share sound video there is no sound.