James Taylor, Chaka Khan and Kris Kristofferson are all on hand to help Joni Mitchell blow out the candles during “Joni 75: A Birthday Celebration,” but it’s Seal who brings the most lavish gift of all, a spine-tingling cover of “Both Sides Now” that makes Judy Collins’ version seem like a children’s ditty.
8:30 p.m. Saturday, TPT, Ch. 2
“The Case Against Adnan Syed” dives even deeper into the same murder investigation that turned the inaugural season of “Serial” into the podcast world’s first blockbuster. Filmmaker Amy Berg, who earned an Oscar nomination for “Deliver Us From Evil,” provides some fascinating updates, but for those who already devoured the 2014 Peabody-winning broadcast, the four-hour running time will seem excessive.
8 p.m. Sunday, HBO
The premiere episode of “Epic Yellowstone,” which focuses on winter in the country’s first national park, should make you fall in love with snow all over again. Bill Pullman’s warm narration will melt your heart as the cameras offer stupendous aerial shots that are too often interrupted by the misadventures of a bobcat searching for a duck dinner.
8 p.m. Sunday, Smithsonian Channel
In “Now Apocalypse,” Avan Jogia (“Caprica”) stars as a sex-obsessed drifter who keeps running into a reptile monster who’s only slightly creepier than his friends that represent the very worst of L.A. stereotypes. If the future belongs to these types of vapid creatures, the end of the world can’t come fast enough.
8 p.m. Sunday, Starz