By default, your video can be embedded on all websites. But if you want you can easily prevent this by following these steps:
Step 1. Go to the Publishing tab of your Video settings
Step 2. Make sure your publication settings are set on Embed only
Step 3. Under the subheading Embedding, you'll find Allow embedding. Choose My websites
Step 4. Below, you find the option to add allowed websites. Fill in the specific domain(s) where this video can be embedded on. Use the complete URL including https or http. For example https://google.com/ instead of google.com.