On the other hand it could be part of a deliberate subversion: Elaine did send the email, but has genuinely reformed and wants to help the MC (along with herself). So this is just more opportunity to make her look guilty (naturally the terms of the will prevent her from explaining her actions at this time), only to reveal later that it really was better for the MC to move out and it was [reader's choice] who's been trying to disinherit the MC the whole time!
I just don't think we have enough information to meaningfully speculate at this point. As everyone has said, nearly every girl in the game could plausibly be the gold digger (Katie and Jenna are the only ones I'd call foul on at this point). Combine that with knowing nothing about the other will conditions, or the gold digger's motives and there's almost nothing we can rule out.
So I think
MrFriendly has the right idea: just focus on judging the girls by their actions and don't fret the will stuff until it occurs. I don't hate Elaine (I'm been mostly neutral with her), but she's certainly done nothing to help her cause: she treated the MC like garbage for years, then overcorrected and tries way too hard to be his BFF (or outright lover, which is just creepy). The fact that this change of occurred the instant she learned about the will conditions is highly suspicious but mostly irrelevant. Even if she's completely sincere, I'm in no hurry to forgive her.
In that case, why not let the MC/Jenna find the video themselves?
If Jolina is 'Dizzy,' it seems very likely she's also the one who knows all the will conditions (since she knew to make the MC visit Monica well before the will conditions were disclosed). In that case she would have ample reason to sew discord between the MC and Elaine early and often, and with as few of her own fingerprints on it as possible. Giving us the evidence herself just calls attention to her own opportunity to tamper with it.
