Before I state the verdict, in future you should provide his STEAM-ID in-game, you can do this by typing 'status' in the console and screenshot the STEAM-ID it provides.
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In the video you have provided, it does show you placing down a C4 but however, he might've saw you placed it down so there is no proof of that. However I have spoken to him about it and hopefully cleared up the rules to him for a better understanding that in future, he should call out a KOS otherwise it would look like RDM so no actions will be taken. I have also spoken to Mytic X Toxic about his name change to 'Mytic X Toxic #Demote4Pixel' and he now understands that it will be not tolerated. This report will go no further as everything has been cleared up I hope.
Feel free to add me on Steam if there is an issue.