Diddy Blasts Cassie's BET Performance, Promises She'll Improve in Resurfaced Video

Diddy's criticisms of Cassie go way back -- long before the infamous hotel beating -- as evidenced in this clip, where he boldly tells fans the singer had fallen way below expectations ... all while she awkwardly sat next to him.

The rap mogul made the video in 2006 -- shortly after Cassie bombed at BET's "106 & Park" performance -- and it shows the two celebs sitting with each other as Diddy admits she had a "whack show."

Despite that, he says, Cassie's going to keep striving to improve in the live arena ... besides, her song "Me & You" was still one of the hottest going in the clubs, he pointed out.

Diddy suggests all the Cassie haters can get down on their knees, pucker up and smooch his backside ... so, outwardly at least, he was standing by his performer.

Many online are now side-eyeing this clip, though ... especially given Cassie's testimony against her ex-boyfriend, and the alleged abuse she detailed.

Check out her reaction to Diddy's criticisms ... she's nodding and even laughing occasionally, but she's mostly just staring straight ahead as her boss calls her out to thousands of fans.

Bill Maher has been a prominent voice in saying Cassie put up with Diddy's alleged abuses for fame ... claiming she made a devil's bargain in order to achieve fame. Prominent psychologists who specialize in abuse have blasted Maher for the take.

Diddy's former employee, Capricorn Clark, talked about Cassie's artistic talents in her testimony last week ... saying she isn't a great live performer -- but, Diddy poured a ton of resources into making her famous.