As in specifically asking for video call to verify your identity by themselves or they just simply asked for a video call without explaining the purpose? If they didn't say that they required it for re-verification --kinda futile at this point given the notary officially appointed by Latvian govt. had verified it, as per their very own requirement-- they probably want the video call to catch you up with their findings and suspicions and invited you to an interactive direct communication so botu parties can discuss the situation conveniently. I suggest you to accept that request, given you've gone so far getting your ID notarized. Few minutes of video call --arguably-- won't hurt. If you declined, though, it'll just made you look suspicious.