My cameras are all installed under the eaves (except one) and I’m not worried about rain, etc. But now I’m about to deploy a couple of battery cam pros. I see there are holes at the back and these are probably for the speakers.
Will rain be a problem? Will covering the holes with waterproofed tape matter? I don’t need the speakers.
I have had 2 battery cam pros outside. One mounted on a fence in full exposure and the other near the edge of the eves.
Neither have had any issues with rain or water entering them. Knock on wood. 
All my cams have speaker holes on the back (I don’t have a BCP though) and never had any issues, even with ones that are tilted downward pretty sharply.
That being said, if there is no use for the speaker, covering with a good tape certainly couldn’t hurt. I doubt those holes are providing any sort of ventilation since then they would not be weatherproof.