A computer-implemented method comprising: facilitating a transmission of video data (208,230) to a first device and one or more second devices (202-2,202-3,202-4); initiating a media effect (110; 122-1, 122-2) according to a device-agnostic coordinated activity protocol, the media effect (110; 122-1,122-2) modifying the video data (208,230) as viewed at the first device and at the second device (202-2,202-3,202-4), where the modification requires cooperation by a device that did not initiate the effect, wherein initiating the media effect (110; 122-1, 122-2) includes a communication server: receiving an instruction from a first device being an initiating client device; identifying one or more second devices being non-initiating client devices (202-2, 202-3, 202-4) to which the instruction is directed and forwarding the instruction to the identified devices (202-2, 202-3, 202-4); receiving a confirmation from each non-initiating client device (202-2, 202-3, 202-4) upon the non-initiating client device (202-2, 202-3, 202-4) determining that the non-initiating client device (202-2, 202-3, 202-4) is ready to apply the effect; and transmitting the confirmation to the initiating client device; and the communication server receiving an application programming interface, API, call (264; 306,310) relating to the media effect (110; 122-1,122- 2) in a data message, the API call (264; 306, 310) made from the initiating client device according to the coordinated activity, the API call (264; 306,310) associated with information (266,268) that specifies a modification to be made to the video data (208,230); the communication server transmitting the API call (264, 306, 310) to the non-initiating client device (202-2, 202-3, 202-4); and applying the effect in response to the non-initiating client device (202-2, 202-3, 202-4) receiving the API call (264, 306, 310). facilitating a transmission of video data (208,230) to a first device and one or more second devices (202-2,202-3,202-4); initiating a media effect (110; 122-1, 122-2) according to a device-agnostic coordinated activity protocol, the media effect (110; 122-1,122-2) modifying the video data (208,230) as viewed at the first device and at the second device (202-2,202-3,202-4), where the modification requires cooperation by a device that did not initiate the effect, wherein initiating the media effect (110; 122-1, 122-2) includes a communication server: receiving an instruction from a first device being an initiating client device; identifying one or more second devices being non-initiating client devices (202-2, 202-3, 202-4) to which the instruction is directed and forwarding the instruction to the identified devices (202-2, 202-3, 202-4); receiving a confirmation from each non-initiating client device (202-2, 202-3, 202-4) upon the non-initiating client device (202-2, 202-3, 202-4) determining that the non-initiating client device (202-2, 202-3, 202-4) is ready to apply the effect; and transmitting the confirmation to the initiating client device; and receiving an instruction from a first device being an initiating client device; identifying one or more second devices being non-initiating client devices (202-2, 202-3, 202-4) to which the instruction is directed and forwarding the instruction to the identified devices (202-2, 202-3, 202-4); receiving a confirmation from each non-initiating client device (202-2, 202-3, 202-4) upon the non-initiating client device (202-2, 202-3, 202-4) determining that the non-initiating client device (202-2, 202-3, 202-4) is ready to apply the effect; and transmitting the confirmation to the initiating client device; and the communication server receiving an application programming interface, API, call (264; 306,310) relating to the media effect (110; 122-1,122- 2) in a data message, the API call (264; 306, 310) made from the initiating client device according to the coordinated activity, the API call (264; 306,310) associated with information (266,268) that specifies a modification to be made to the video data (208,230); the communication server transmitting the API call (264, 306, 310) to the non-initiating client device (202-2, 202-3, 202-4); and applying the effect in response to the non-initiating client device (202-2, 202-3, 202-4) receiving the API call (264, 306, 310).