The Class 90s Lights are actually the new class 90 lights the British Rail class 90 had glass over the lights wich can be seen i pictures from the early 90s.
The Class 90s have another consist with the DVT, the 90 + DVT and DVT + 90 both include them, it's just the Top n' Tail that have Class 90s at both ends
Im pretty sure the last fact is true of the class 91 irl but im not sure about the class 90, since the class 90 was designed for freight as well as passenger services
The final fact is incorrect. 90's did run Top and Tail with trains sometimes, although the idea probably came from LSL running a charter along the WCML as a replacement for avanti.
The wrong dvt was shown in the Video the dvt in the Video is the Intercity 225 dvt wich is only used by the class 91 but the class 90 and all other intercity locos pulled the class 82 dvt.
