An example device for processing video data includes a memory configured to store video data; and one or more processors implemented in circuitry and configured to decode a supplemental enhancement information (SEI) network abstraction layer (NAL) unit of a video bitstream including the video data, the SEI NAL unit containing a motion constrained tile sets (MCTS) nesting SEI message; determine that the SEI NAL unit does not contain any non-MCTS-nesting SEI messages in response to the SEI NAL unit containing the MCTS nesting SEI message; and decode subsequent SEI messages of the SEI NAL unit as MCTS nesting SEI messages in response to the determination.