Do video ads convert better than image ads on facebook ads?

This is not the kind of question that has a definitive "yes" or "no" answer.

Just test, usually the videos are better, but it's not a rule.

Generally short, direct videos convert better for me.

It depends on what you create the "PERFECT" (The Image Or The Video). Most of the people follow the image Ad, example in fraction of second if the image gives answers of many questions. In same way way maximum number of people never play whole Ad.

The advantage to a video ad is that you can take a little time to explain your product and have longer to convince them to purchase your product if it is engaging. Usually you need to first use an image ad that gets enough attention that the viewer will want to know more by watching a longer video ad, which will hopefully lead to more engagement and product purchase. It's a progression.
If you can only do one or the other then yes it depends on your product or service and A/B testing is the only way to know for sure.

A video thumbnail can entice someone to click an ad to see more than plain graphics.

Test both and see what's works best for you

Yes, Videos graps attention greater than images so does for conversions

It depends on your viewers, If they like pictures on your website, you should continue . About video, I think trending video can helps you appeal to others come your website