If Saussure and Derrida were alive today they would have loved Periscope (well, maybe not).
Perhaps currently the most significant live broadcast service Periscope brings interaction to video by combining live streaming with (not so) old-fashion text chat. This is why it made sense for Twitter to invest in Periscope.
By separating (or rather merging) the medium of speech and writing Periscope was able to solve the problem of authorial voice. Scopers speak. Viewers type. It is such an elegant and simple solution. Skype had tried but was not able to resolve this conundrum with their effort more than ten years ago. Everybody spoke and nobody was heard. Now everybody communicates through two clearly defined mediums and all are happy.
Well done Periscope.