Video share

Using the zoom app on an iPad Pro/OS 15.2.1 and have not been able to share a video from the iCloud photo files. 

At best, I would see the video on my screen with very low volume sound and those attending the meeting will only see a gray square.  I have reviewed the technical info online which provided no solution - and left me wondering where I can find the “advanced features” section when attempting to share. 

Are video shares technically feasible from the iPad? Or is this feature limited to computer based zoom sessions. How do I control the sound volume?

Thanks

john