@Pathduck @vgracanin I certainly don't need one either (and that type of camera would just be a pain to use here in Norway, the placement of it (where it would have any kind of realistic usage) would have to be declared with proper signage, etc.
As I mention above, this is likely some kind of CSS styling issue, in which case the problem is likely in the web page itself, not Vivaldi.
Just to mention one possible scenario for such an issue:
Vivaldi's UI is working like a web page (which other browsers don't).
AFAIK (I am an under the hood dev, not a web dev) CSS styling have several types of ways to specify an offset for an element that is being displayed, such as an image, relative to some kind of box.
What if, hypothetically, these pages (accidentally) place the camera image, not relative to the border of the video frame location border, but what it "thinks" is the absolute position of the image relative to the page's upper left corner , but instead specifies it relative to the UI's upper left corner? (Or even the upper left corner of the display?)
One way to investigate this possibility is to look at how big the offset is, when taking in to account the GUI borders.
Neither of the images above actually shows the Vivaldi GUI, so I can't say for sure, but just guesstimating by eye (and assuming no scaling of the image), both images seems to have a vertical offset that looks similar to the combined vertical height of my tab bar plus the address bar, and for the one where there is a horisontal offset, the offset seems to be similar to the width of the vertical sidebar for the panels, when the panels are not displayed.
So, here are a couple of experiments that could prove, or disprove, my hypothetical:
Check if my "measurements" are correct, use your actual GUI to compare (Tip: the screenshot functionality can be used to take images of the GUI, not just the page)
Try to use the page in full screen mode, possibly removing the GUI as a factor. Does that change the placement?
One could try several other GUI elements, such as opening a panel (e.g. bookmarks) and see if/how that affects the placement.
What happens if you resize Vivaldi to a non-maximized form, and perhaps resize the browser window so that it the whole camera image don't fit inside the tab, and you have to scroll.
Also, what happens if you move the non-maximized browser window around?
Finally, another way to obtain information, is to use the developer tools to inspect the styling (specified, or computed) of the page, especially the image display area.
If my hypothetical has any relevance whatsoever to what is going on, the steps above should find an indication of what the problem is.