Do both parties have to have Messenger Plus to send and receive icons, emoticons, videos, sound, etc?. I tried to send an emoticon to my friend and he didn't understand. He does not have Messenger Plus.
This because stuff like custom emoticons, winks and sounds are not part of Skype. They are added by Messenger Plus!. Thus Only Messenger Plus! knows how to interpret/play them.
Cookie is right but if you have Messenger Plus! for Skype and make a video call to someone who has Skype (but not Messenger Plus! for Skype), he/she CAN see animations and video/sound effects.