Hideo Kojima struggled to get live-action clips in Metal Gear Solid, not for technical reasons but because of a lack of contacts.
In a series of tweets on his Japanese account, he shared some background information on the game celebrating the 35th anniversary of the series (thanks SiliconEra).
Kojima wanted to push the realism of his fictional story using real war footage and, of course, the PlayStation console was able to play compressed film so this wasn’t a technical limitation.