Tap the Add Photos & Videos button inside a Circle to open the Media Picker. Select the media you wish to add to the circle.

 

Photo Resolution & Video Length
Photos are compressed and resized to a maximum of 3 megapixels. The maximum video length is 60 seconds per clip (defaulting to the first 20 seconds). Video resolution is 720p. Higher resolution and longer videos are available to our Business Platform customers.
 
Photo Library Permissions/Access (iOS only)
When adding photos & videos from the media picker, be sure to allow full access to your photo library. Otherwise, the media picker will only have access to a subset of your photo library, requiring a two-step selection process of allowing visibility to the photos, followed by actually adding the photos to your circles.