To re-seal RV windows on my 2006 Jayco, I simply followed the instructions within:
A- I removed the factory window "rubber foam" (located behind the window's lip) and replaced within butyl tape (available at RV parts stores)
B - Instead of silicone bead on window's outer upper window lip, I used RVProflex product (also available at many RV parts stores) instead.
C - As seen in the video, very easy 2 person DIY task. Especially if using a cordless screw driver.
Clean, simple and easy. Especially doing 2 x windows each weekend.