For me.. first video is (probably) regular boot up, if you have "click-click" on a playfield G.I. (&relay) possibility is better.
(in this solution, I suspect on DIP switches problems for credit display, and maybe some others functions)
The second video indicates (expected ? ) problems with (only display's ?!?? ) connectors
Question...after boot-up (first one is there any "high score to date" numbers on displays ?
Starting a game... are you 100% shure in additionally wiring ?
(BTW, did you check "test mode" ? )
Greetings from Croatia