Video signal attenuation
I will assume your source is 2V unterminated and the source impedance is 75Ω (ie your source will deliver 1V into a 75Ω load), but it's not clear whether you want 0.75V terminated or unterminated.

Also, it's not clear whether you are dealing with composite video and if so, whether you are OK with attenuating the syncs or not. To correctly attenuate a composite video signal you would need to strip the sync pulses, attenuate the remaining video signal and then reinsert the sync pulses at full amplitude (which is not hard but much more work).

Assuming you just want to attenuate the entire signal, the conventional way would be to use a 'T' or 'PI' network. The advantage of these arrangements is that the input and output impedances can be matched to the system (so you could mount the resistors on a board and connect the circuit in with lengths of 75Ω coaxial cable).

Here are two 'T' attenuators which will give approximately 0.75V into 75Ω and 0.375V into 75Ω respectively (using E12 preferred values so the results are not exact).