It depends how the record is capturing the game - many recorders will do what FBX does and capture directly from the game as this gives the best performance but adding support for this for older versions of DIrectX can be a lot of work with lots of game-specific fixes required. For that reason, DIrectX 9 often tends to be the cut-off for how far back support goes.
ShadowPlay works for you because NVidia can take advantage of a special feature on their graphics cards that allows it to bypass DirectX altogether when recording.
Other recorders that have a fullscreen record mode should also be able to capture older games like Unreal Tournament because the methods that they use will also bypass DirectX but their performance may not always be as good as ShadowPlay (on more recent games that are more resource intensive anyway) because they don't have access to some of NVidia's features.
We reckon the fullscreen recording mode that we're working on should be pretty close what ShadowPlay can do though and I doubt you would see any difference when recording older games like Unreal Tournament.
