The webcams come from TfL (Transport for London). They are otherwise known as Jam Cams. They show a short video clip of about 10 seconds duration and update every ten minutes. You will have to refresh the page to see updated videos. In some case you might have to close the current tab or close the browser then open it again to see the latest video. On a PC or laptop, try hitting shift (or control) refresh.
Sometimes a camera feed isn't available and you will see the message "Camera in use keeping London moving". In such a case the feed gets restored later.
The camera positions change from time to time which means the description might not always be relevant to the scene you are viewing. They do tend to have one position that they stick to most of the time.
The webcam videos are quite low resolution, 352 x 288 pixels. That's the way they come in from TfL. They look good on a small screen such as a phone. In any case, you get used to it.
Here's a link to this page: londonwebcam.co.uk