Harvestman, which are common in the woods of southeast Pennsylvania.

Genus Leiobunum looks like the best match, which is the only place on bug guide I've found eastern U.S. harvestmen with the distinct orangy/medium brown body, very black legs, and proportions of relatively small body with thin legs.

Leiobunum nigripalpi seems most likely so far, but it's the only one with this appearance I've found a good species description for.

Also looking for more info on and photos of L. serratipalpe and L. verrucosum.

Genus is probably as far as I can take this blurry, tiny photo.