streets of a refugee camp just miles from president bashar al assad's palace in damascus. ateek atika shubert is "outfront." >> reporter: this video is proof, isis says that they are just miles from the presidential palace of bashar al assad. this is the closest isis has gotten to threatening the seat of assad's power by striking at one of the most vulnerable populations in damascus the palestinian refugee camp. now, reports from palestinian leaders that isis is staking its claim by beheading rival rebel commanders inside the camp. the u.n. is calling the situation, quote, beyond inhumane. >> when we think of a situation that was already unparable in many terms, in human terms when i visited three weeks ago, the situation now has only deteriorated further and so it