How to ADD a delay to coaxial tv signal?
OK, let's assume you're talking about an analog signal that has a bandwidth of about 5 MHz, and you need to maintain a signal-to-noise ratio of about 72 dB, or about 12 bits of resolution.

One direct way to delay the signal is to digitize it, write it to a memory and then read it out again at a later time.

To capture a baseband signal with a bandwidth of 5 MHz, you'll need to sample at a minimum of 10 M samples/s. To delay this by up to 10 seconds, you'll need 100 M samples of storage. Call it 200 MB for convenience. SDRAM would be an excellent fit.

You need an ADC, the SDRAM, and a DAC, plus some sort of control interface. You can get fast MCUs, DSPs and FPGAs that all have the necessary SDRAM and I/O interfaces. The choice of what kind of chip works best for you depends on whatever else (if anything) you might want it to be doing.