Opamp, Amplify square wave or video
Your signal is all positive, so you can amplify it around 0 to get what you want.

The issue is that not all opamps work with their inputs at 0, or can drive their output to 0.  What you want is a rail to rail opamp, or at least one where the common mode range extends to the negative rail, and the output range also extends close to the negative rail.

Onother issue is the bandwidth of video.  The opamp would need to have probably 20 MHz gain-bandwidth to be able to amplify reliably by 2, but more would be better.  There are opamps specifically intended for video use.

If you do have to shift the DC level, you can get it back.  What you show is actually biased up so that the sync tips are at 0.  A "normal" composite video signal has negative sync tips with the front porch being 0.  This is because the size of the sync tips can vary and are not guaranteed relative to the picture information.  However, the front porch is specifically the black level.

Consider that TV signals received over the air don't have any inherent DC bias.  The waveform was designed so that relatively simple analog circuitry could fix it's DC level after reception.  This is done by detecting the sync tips, then clamping the waveform to 0 a short time after the trailing edge of the sync tip.  This is called a DC restorer circuit, and you may be able to find ICs that do this for you.  Back when composite video was more common, there were easily available ICs for detecting and stripping out vertical and horizontal sync, and DC restoring.