If I use the same video on different posts on my site, does Google consider it as duplicated content?
If you are talking about YouTube video that you own and want to add it on multiple posts on your website, then it is not an issue!
You can read here more,
Hi gauravk, thanks for your answer! what if I don’t own the video?
Better to take permission from the YouTube video owner, as he/she may send you DMCA for your post, if he/she does not want to share his/her YouTube video on your website!
@Sophie Edited: Generally, people don’t mind if someone is sharing their videos on website, as it will help in getting more views and subscribers for their YouTube Video!
I will try to share it only once, but that doesn’t mean I shouldn’t ask permission, but in this case that person is not reachable. Thanks again!