April has officially arrived, which means there's a whole new crop of streaming options for you to dig into. What are the highlights? Our Stream On picks this week direct you to Netflix's one-hour "Derek" special, featuring the outrageous mockumentary-style antics of the hilarious Ricky Gervais. There are also a few movies to feast your eyes on, including vampire battle extravaganza "Underworld" and the Bill Murray fave, "Groundhog Day." Happy streaming, everyone!