Two things have to say yes: the browser has to allow this site, and
your computer or phone has to allow the browser.
On a computer
Allow this site in the browser. In Chrome and Edge,
click the icon at the left of the address bar, switch Camera and
Microphone to Allow, and reload the page. In Safari, open Safari →
Settings for ohsovideo.com (or Settings → Websites) and set Camera
and Microphone to Allow. In Firefox, click the crossed-out camera or
microphone in the address bar, remove the block, and reload. If you
closed or ignored the browser's question a few times, Chrome stops
asking and blocks the site quietly: this is the fix for that too.
Allow the browser on a Mac. Open System Settings →
Privacy & Security → Camera, and turn on your browser. Do the same
under Microphone. The browser may need to be quit and reopened
before it notices.
Allow the browser on Windows. Open Settings →
Privacy & security → Camera, and make sure camera access, "Let
apps access your camera" and "Let desktop apps access your camera"
are all on. Do the same under Microphone.
Close anything else using the camera. Zoom, Teams,
FaceTime or another browser tab can hold on to it, and on Windows
only one app can use a camera at a time. Close it and reload.
Wrong camera or microphone? With an external webcam
or microphone plugged in, pick it in the same place you allowed the
site: the icon at the left of Chrome's or Edge's address bar lists
each device.
On a phone
Android, in Chrome. Tap the icon at the left of the
address bar, then Permissions, and allow Camera and Microphone. If
the page says Chrome itself isn't allowed, open your phone's
Settings → Apps → Chrome → Permissions and allow both. Also check
the Camera access and Microphone access tiles in the quick settings
you pull down from the top of the screen: when they're off, every
app is blocked.
iPhone, in Safari. Tap the page menu at the left of
the address bar (the icon with the lines), then Website Settings,
and set Camera and Microphone to Allow. If that doesn't help, open
Settings → Apps → Safari, and set Camera and Microphone to Ask or
Allow.
iPhone, in Chrome or another browser. Open
Settings → Apps, choose the browser, and turn on Camera and
Microphone.
Still stuck? Reload the page, or open it in a new
tab. If it still won't start, try another browser: Chrome, Safari,
Edge and Firefox all work.