Re-rendering 4k videos (or of any other quality fwiw) with ads included would probably incur more electricity costs than they could ever make through the ads. TV could afford to do this since they transmit the same program and the same ads to everyone. Youtube targets them per user, so they’d need to render the same video, in high quality, every time any user clicks on it.
The radar you’re talking about is a pulse-doppler radar. It doesn’t see things the same way your eyes (or a synthetic-aperture radar for example) do and it’s not down to filters. A P-D radar observes and measures the Doppler effect which only occurs when the object is moving and determines the contact’s velocity, heading and altitude based on that. A jet flying vertically at 0 GS would probably be detectable, although this would be difficult since, as you said, it’s not moving directly towards or away from the radar.