Here’s Michael Cera’s brand new short film “Gregory Go Boom,†which was just released today on JASH, the YouTube comedy channel Cera co-founded with Reggie Watts, Tim & Eric, and Sarah Silverman. Written and directed by Janicza Bravo, “Gregory Go Boom†stars Cera as a paraplegic guy trying to find independence. Sarah Burns and Brett Gelman also star. This is Michael Cera’s second short film for JASH, following “Brazzaville Teen-Ager,†which debuted last month, just in case you want to have yourself a very short Michael Cera short film marathon.