One needs to check their camera software setup and instructions.

Hi, is this on a website like Google Meet, etc.? If Firefox doesn't ask you automatically, you can use this method to give the site permissions:

While you are on a page on the site, call up the Page Info dialog using one of these methods:

• Ctrl+i (for Mac, Command+i)
• (menu bar) Tools > Page Info
• click the lock icon in the address bar, on the drop-down click the > button, then at the bottom click "More Information"

When the dialog comes up, click the Permission icon at the top to show that panel.

Scroll down to "Use the camera" and uncheck the "Use default" box, and then select "Always ask" or "Allow" depending on your trust for the site. Repeat with "Use the microphone."

Does that work where you need it to? If not, are there any error messages?