Systems and methods are provided for integrating supplemental overlay content within streaming video content that is to be broadcast to viewer devices. The overlay content to include in the streaming video content may be dynamically determined during video streaming and incorporated within individual frames of the video data, such as by a computing device of a user who is broadcasting his play of a video game or other activity, prior to the user's computing device sending those video frames (with embedded overlay content therein) to a streaming platform to be broadcast to potentially many viewers' devices.