The low memory warning is letting you know that your device is critically low on RAM. Make sure you close all other applications from the multi-task menu by following this procedure.
1) Save your work.
2) Press the home button to go back to the home screen.
3) Double click the home button to show any apps running in background. Click here for more information on how to close apps.
4) Press and hold iForm until you see the red dash mark in the upper left hand corner.
5) Be sure to close iForm from background menu. DON'T DELETE FROM THE HOMESCREEN (as this will completely remove the app from the device).
6) Restart iForm, and open the record you were previously working on.
The notification was added to the platform to let you know of this situation. This is not a bug, as it is a limitation of the hardware. Capturing media files requires more resources than a text field so you will encounter this more on older devices that have forms with lots of media.