I finished the job and delivered the video to the client, and I did not hear a word from him 3 days ago,
so today, while I was looking for another job, I decided to look for the site he gave me to put in the video he asked for,
and I found that my video was used
is there something to do?
and it's a fixed price job
Was the job funded? Did you submit your work using the right function and not with a simple message?
If you did, don't submit again. 14 days and you will receive your money (or before, depending on the client).
I only see 1 job in your history. Is that the job?
If so, money in escrow will be released automatically, then you will have to wait a bit longer to have access to the money. It can be up to 3 weeks in total from the time you submit the work to the time the money is in your bank account.
re: "and it's a fixed price job"
This means you did something wrong.
A client can not simply choose to "not pay" you for your work with a fixed-price contract... unless you set the contract up improperly.
It is important that you figure out what your mistake was, so that next time you work, you can set the contract up properly and ensure payment.