You will notice there are several areas where he saves & then loads. Typically this is to ensure you get the right hireling or potion in the shop or whatever. The comments on the vid say he reloads until he gets what he needs then stitches it together. Theoretically this is what could happen if you get the right spawns first time.
Given he's up front about the reloads, wouldn't make sense to hide having cleared something out beforehand "off-camera". I've done that Eeofol run myself (with many reloads) to I can vouch for its possibility: although the very last bit before the exit to Eeoful is tight & you need everything - including the Behemoths' tacking movement - to go just right