First of all, check that you have followed our advice: see the dedicated article.
You are trying to register from your computer
This is probably a problem with your browser.
It's easy to fix. Copy the link of your Visiotalent registration page and paste it into a new browser (preferably Google Chrome or Mozilla Firefox).
If you still have problems, you can always do it from your smartphone or tablet.
You try to register from your smartphone or tablet
Make sure you have enough space to temporarily store your video before sending.
However, if this is not enough, you can always record yourself from a computer with a camera.