Yes—VoiceThread is a great tool for annotating video, and it would work well regardless of whether students were completing the activity during class time or asynchronously.
How do I set up a Canvas assignment when students are submitting a Google Doc?
This question that comes up a lot because the assignment submission options are kind of oddly named in Canvas. In your assignment’s settings, scroll down to the Submission Type box, and select Online on the dropdown menu’s options, then select the Website URL checkbox.
How do students submit a video?
Students can upload and embed a video directly via Kaltura My Media in the textbox editor that appears in both Canvas discussions and assignments.