WASHINGTON — President Barack Obama says there should be an investigation into the hidden-camera video involving employees at the activist group ACORN and a couple posing as a prostitute and her pimp. The two ACORN workers are seen apparently advising the couple to lie about her profession and launder her earnings to get housing aid. The video is only the latest problem for the group, which had nearly $1 million embezzled by its founder's brother and has been accused of voter registration fraud.