The simplest black level clamp consists of a signal diode (1N4148) reverse-biased to ground from the output line of the input buffer above and a 4k7 resistor in parallel with it. That forces the sync tips to be at (gnd - threshold voltage of the diode), which shifts the black level of a 2x amplified video reasonably close to ground. Add that and you can connect the two circuits  together and see how they work. They should be very good as far as the signal quality goes (maybe not broadcast quality, but no visible signal degradation). Don’t forget good power supply bypassing, use at least 220u of electrolytics and 100n ceramic caps near the transistors on both circuitssource

The design is based on a switchable array of six Maxim MAX4258 dual-channel video multiplexer-amplifiers.Gain-change settling time is lower than 30 nsec. The greater-than-100-MHz bandwidth of each stage results in an overall passband for all gain settings of greater than 60 MHz. The five lowpass-bandpass capacitors, C1 through C5, determine the lower end of the passband.source

The circuit transmits 200MHz (-3dB bandwidth) video signals while stripping off the sync pulse and performing DC restoration. It is configured for a typical video cable driver application driving a double-terminated 75Ω load, where the EL8102  is configured for a gain of +2 to ensure unity gain throughout.source

Here is the simple Video amplifier.Part List are used :R1=1Kohm C2-6=100uF 25V C6=100uF 25V R2-3=12Kohm C3=100nF 100V IC1=LM359N R4-5-6=10Kohm C4=1pF ceramic J1-2=BNC connector C1=10nF 100V C5=10nF 100V.source

The LM1823 is a video I.F. amplifier designed to operate at intermediate carrier frequencies up to 70 MHz, and employ phase locked loops for synchronous detection of amplitude modulation on these carrier frequencies. The high gain, wide AGC range and low noise of the LM1823 make it ideal for use in television receivers, video cassette recorders and in cable TV set-top converters requiring high quality detected base-band video and an audio intercarrier. source