Q. My teacher can neither see nor hear my video in VoiceThread.

VoiceThread can not import .ppt slides with video.

When using VoiceThread, the best way to do a PowerPoint presentation is illustrated here… https://use.vg/TMKGUk

In the interest of you not having to redo your presentation, hopefully this solution will work for your instructor to be able to hear and see your video components.
https://use.vg/aJWh2O