Ebert lost his battle with cancer earlier this month (04Apr13), but his widow Chaz decided to go ahead with the reviewer's yearly movie celebration in the town of Champaign.
Swinton ensured the 2013 Ebertfest was a joyful occasion by recruiting 1,500 film fans for a dance-along to Barry White's You're the First, the Last, My Everything down the aisles of the Virginia Theater - the cinema Ebert frequented as a youngster.
She told the crowd, "We're not dancing up here (on stage), because if we dance up here, you're just gonna sit and watch us and laugh. So no observers allowed, participants only. It's a service, this is a spiritual service!"
The Oscar winner bounded down the stairs and into the audience, before making her way around the venue leading a conga line through the aisles.
Afterwards, Chaz quipped, "That's why she's one of our favourite festival guests. There's nothing better than having 1,500 people dancing along to Barry White."