I'm repairing a tv and there's an old molded paper capacitor that's rated at .00082uf (820 picofarad) with a max voltage of 2000v. I can't find a film capacitor of that value at my local electronics shop, so in wondering if I could just use a disk capacitor in its place

Is it tubular or domino shape? If domino it may be mica, and still usable (the color code should reveal the type). Ceramics often are not good for TV work, and should be avoided in video, synch, and deflection circuits.

You do know there are lots of online parts vendors you could check, right?