[Another Update] It turns out that I may have injured my DVD player somewhere along the line, as I attempted to hook it up to a modern tv that I have, and it produced the same results, no picture without the BVAM5 car amp, and a marginally good picture when used with the car amp, even though the video output waveform looks fine.
Either way, I returned to the method that fzabkar stated, only when I first attempted it I omitted the coupling capacitor as I achieved a better picture from the game console without it. However, other signal sources simply would not work without the BVAM5 car amp. In reality, this is because my capacitor was way too small in value, (100pf) and did not do a good job of isolating the composite input. A 470uf seems to be doing the job, as well as a 75 ohm resistor behind it across the cable for input sensing on an adapter I have. So in hindsight, fzabkar's method would have worked fine, had the TV and DVD player been working, and I knew what size capacitor to use.