My guess is 3 team gameplay videos -Japan, FF, Yagami- uploaded at noon JST (May 6th) on the official SNK Youtube for linking on the game site (they will show up on the international PlayStation channel some hours later I guess), because that would leave 15 gameplay videos -the remaining 13 teams and the 2 bosses- for launch each Friday, and once May 6th goes we'll exactly have 15 Fridays before the game release week. I'm insisting on Friday because SNK uploaded teasers on their own channel on Fridays at noon JST.
I don't feel like taking guesses about non-team trailers and KOF Station, those sections have 4 slots each but SNK could edit them, you never know...