The ornamental design for a webcam mount assembly, as shown and described.
FIG. 1 is a front perspective view of a webcam mount assembly of my new design.
FIG. 2 is a top view thereof.
FIG. 3 is a bottom view thereof.
FIG. 4 is a left side view thereof, the right side being a mirror image.
FIG. 5 is a front view thereof.
FIG. 6 is a rear view thereof.
FIG. 7 is a front perspective view thereof mounting to a computer monitor; and,
FIG. 8 is a rear perspective view thereof.
The broken line showing of the Computer Monitor is included for the purpose of illustrating environmental structure and forms no part of the claimed design.