The chain would probably break before the bitter end shackle, as chain cable is very susceptible to parting when shock loading. That's why there is always considerable attention to anchoring a commercial vessel and the chief officer should be in charge of the anchor party. In my career I have partied twice the anchor cable, once when we fouled a wreck and overloaded the chain on recovering the anchor, the other time was north of Anglesey when the boatswain let go off the anchor by accident when the vessel was doing about 11 knots. The last I lost my anchor which was about 7cwt, my manager wanted me disciplined over the matter as I was the master. I had to go into port for the windlass to be surveyed by Lloyds and get a dispensation letter from them to sail why a new anchor was located for the vessel, lost 4 days work time. In the video clip you can see the cable break on the gypsy, could have picked up a clump of cable which jammed under the hawse pipe in the cable locker, another problem when paying out chain, if it is not used a lot it rusts welds into clumps.