Rachel Fleit’s “Introducing Selma Blair,” a doc on the titular actress, is what one might qualify as an uneasy watch. Blair was diagnosed with multiple sclerosis in 2018 and we can already see in the first scene the physical effects of the MS, as Blair’s speech slurs and her body breaks down during interviews. And yet, it’s the actress’s spirited personality that makes the film somewhat less harrowing to watch. Eventually, Blair travels to Chicago for a risky stem cell transplant that could either tame down the M.S. or kill her. Beforehand, she makes plans for her own funeral, hiding the emotional and physical pain from her young son so he won’t remember her “like this.” Director Rachel Fleit, given incredible access to the actress, shoots Blair’s grueling five days of chemotherapy at the clinic, the goal is to break down her immune system so the treatment can build it anew again — some of the film’s toughest scenes come through in this segment. The result is incredibly intimate stuff and a testament to Blair’s courage and strength. [B+]