In this FlashForward clip, Mark testifies before the Senate. He doesn't exactly enjoy doing it, as you can see.
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This is a FlashForward clip from the episode "Gimme Some Truth." In it, Olivia confides in Aaron about concerns over Mark.
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This is the official ABC promo for "Give Me Some Truth." During the episode, Mark speaks to the Senate.
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FlashForward Season 1 Episode 5 Quotes

Mark is an alcoholic, Olivia. He doesn't need a reason to drink. He drinks because he drinks.

Aaron

If you can't trust Mark, who can you trust?

Aaron