I think this is a serious problem with ROM which has gone unnoticed and unfixed. The same thing happened with my phone too. The memory became corrupt and no matter what I tried I couldn't recover it. I had to eventually replace the motherboard to get my phone working again.
This ROM has a problem which causes random reboots and then one of the times you will eventually encounter the problem you have explained and shown in your youtube video. The devs needs to look into it.
A ROM CAN'T BREAK YOUR EMMC. The memory corrupt thing is EMMC failure and (some) note 2 and 4 are prone to it. You can test your chip after flashing an mm ROM using EMMC check(App doesn't support nougat yet) to check if your device's chip is fine. I've used this ROM before (Not using it now) and the only problem I faced (somethimes) is battery drain and maybe some lags at some cases. Random reboots are understandable (could be caused due to old BL/modem)
Two images of sane vs insane chip related to the EMMC bug has been attached.
Please note that Samsung released a kernel patch at sometime during 2016/2017 which patches the insane chip to solve the problem. But if you have the defected chip, you might end up having EMMC error eventually.
I repeat once again, a ROM like this CANNOT break your EMMC