Young's penalty broke the deadlock early in the second half and, after an own goal from Rovers defender Grant Hanley, Downing also got on the scoresheet before Nikola Kalinic's consolation.
Young's stunning strike completed the scoring eight minutes from time and Blackburn skipper Ryan Nelsen was sent off in injury time for a second bookable offence.
The home side's dominance was finally rewarded after 49 minutes with Young putting Villa ahead via a penalty. Keith Andrews lost possession to Young and the Rovers defender brought down the England player. Young stepped up to send Robinson the wrong way.
After 62 minutes, Hanley could only deflect a low centre from Marc Albrighton past his own keeper and then Downing cut in from the left after seizing onto Albrighton's pass to coolly beat Robinson with a shot into the far corner.
Kalinic scored a consolation but Villa had the final say when Young scored his second with a first-time shot that flew past Robinson and Rovers` misery was compounded when Nelsen was dismissed late on following a second yellow card.
Source: PA
Source: PA