They do a ton of training for the event, going over the what ifs. Then put in hours in the sim rehearse for those emergency events.
Of course they do practice low level flying all the time. Its the C17 that I consider spectacular, flying that huge transporter low level up the river is truly amazing. Sort of like a fleet of busses doing the Bathurst track at 150KPH..
The best comments on the videos come from the Yanks. The ones that say it cant be done, no one is allowed to fly that low, must be CGI.. :)