Many times paper is set behind plaster , sometimes 15 lb felt, this did not have asbestos,
if it is thicker ground & compressed paper that was used for a while in the 30’s and 40’s that stuff was easy to burn so it probably did not contain asbestos. To know for sure it would need to be tested, panel by encapsulated and then covered would make it safe if it was asbestos. I would treat any popcorn ceiling like asbestos as most did have it.
HDMI and speaker wire are basically signal wires, not power wires. Both the voltage and amperage is very low. Indoors it is safe to run these hidden or exposed without channel or conduit if they are properly rated. See this Q&A for a discussion of proper rating.
When channel or conduit is used, it is either for convenience in handling, and to keep the wires away from other materials, or it is used to improve the aesthetics - channel can be painted and looks neater than cables.
There are limits as to how much signal wire can be run in cable or conduit, but this is generally a function of pure physical space and ability to pull wire, rather than heat or safety. Speaker wire can be tacked to baseboards or other molding if that works. be careful to avoid breaking the insulation or the inner wires when stapling, and if you put wire under moldings, be careful not to nail through. Its not a danger issue, is a broken wire/no signal issue.
Power, including extensions to run a projector, is very different. No code allows extension cords to be buried in wall. I don't think any codes allow extensions to be tacked to baseboards. Also power cables should not run parallel to signal wires - they can cause interference even though many signal wires (like HDMI) are shielded.
You need to bring a regular, properly installed power line to the projector. This can be properly installed NM cable inside a wall to an outlet box. It can be surface wiring, but this requires standard metalic surface channels and boxes such as this and this:
One other note. Lampcord is often used as speaker wire. It is the same as is used for AC power cords and small extension cords. If you are using such wire, be careful, if you are burying in walls or stapling, that it is speaker wire rather than power carrying wire.
Best Answer
There's no way for anyone to say if there's asbestos in it by looking at it. You'd need to get it tested.
Is it a worry? Probably not. It's not friable in this state, so poses no real risk. It's only if you disturb it that it becomes an issue. For the amount you'd have to disturb to mount a projector I'd not lose sleep over it. If you must work with it a little bit, wet it down good before cutting/drilling (spray bottle--cuts down on dust), wear an appropriate mask (make sure it's asbestos rated), and get an appropriate filter for your shop-vac (also asbestos rated).