it's probably just me, but i don't understand what you want. i'm sorry.
i do understand you want to run a b4a app on your pc (bluestacks). fine.
you say "some browser"; i assume you mean "webview" (which is not a browser).
the part about camera and another emulator and webviewextras and an image make no sense to me. can you explain a little more?
what does the camera have to do with it?
what are you trying to do with the image?
where does the image come from? (if not from a camera somewhere)
what is it that you think webviewextras will do for you?
on the one hand you say:
the intention is that it can use any application that uses a camera
then you say:
can you replace the camera capture
if you want to replace the camera capture, why do you want a camera in the first place?
if you're asking whether it is possible to send an image to a webview (presumably, with webviewextras), the answer is yes. (assuming bluestacks supports it. you won't know until you try. don't forget, bluestacks is an emulator. there are limitations.).