In the video "Adam Savage's One Day Builds: Making a Puppet" (Link: ) they use beads in the arms to make them more flexible and movable. I would like to do this for a puppet I'm making but I'm not completely sure how to do that. Does anyone know how you would go about doing this? Thanks.

Just take beads and string them on a piece of cord. Put a knot in between the to keep them flexible or make sure you don't string them too tight.

It's a great method for dynamic movement, I think in the video they actually sew a tube of fabric, then sew one end shut, add a few beads and sew a few centimeters in from the closed end to create a little pocket with a few beads in, then repeat the process maybe 10-15 more times until you have a length of fabric with little bead filled pockets running the entire length.
I've used this method a few times and I it has its place when you need lovely slightly weighted floppy arms, but I still like segmented arms that bend only at the elbow.