This article is intended for Citrix administrators and technical teams only.

Non-admin users must contact their company’s Help Desk/IT support team and can refer to CTX297149 for more information.

Multimedia redirection is disabled on RfLinux after installation of RMTE. 
Environment:
Receiver for Linux 13.X.X
Citrix Workspace app for Linux 1808 and 1809
RTME 2.7 (or older)

Problem Cause

Multimedia Redirection is disabled by RTME 2.7 (or older) to avoid Race condition between RTME and Receiver for Linux / Citrix Workspace app for Linux with Video Capturing devices.

https://docs.citrix.com/en-us/hdx-optimization/current-release/overview.html 

"On Linux terminals, the RealTime Media Engine 2.7 (or older) installer disables multimedia redirection in Linux Receiver. Thus, avoiding the Optimization Pack and Linux/Unix Receiver getting into a conflict when accessing video devices. "

Please note that any application in the virtual desktop that needs to access the webcam has to be 32-bit, since this is the only configuration supported by Citrix Workspace app for Linux at the moment.
You can use a 32 bit browser to verify webcam redirection online (e.g. www.webcamtests.com)

In Linux terminals, webcams are used in exclusive mode by the application.
For example, if Firefox is using the webcam and GoToMeeting needs to be launched, the Firefox tab has to be exited and then launch GoToMeeting to use the webcam.