Typically the way Chromecast apps work is that when the video is playing you can click in upper right hand corner to start playing the video. However with Doggcatcher you have to enable/cast Chromecast before you even select the episode. There is also a bug in that after you start playing the video then decide to cast the play bar reverts to the previously played podcast.
So imagine you are at main menu you then find a podcast click on the list of episodes then find the episode you wish to play click play then start watching oh hey this would be cool on the tv you go to cast but cannot (no icon) so you back out to list of episodes then back out to list of podcasts then find the cast button click on it.... unfortunately now that it's casting you cannot simply click the play button as it's set to play some random whatever you listened or watched prior to this episode. So you now have to go back through all the steps choose podcast choose episode hit play and now it's playing on the tv. A lot of steps that could be eliminated had the chromecast icon been were most have it in the upper right hand corner of whatever video is playing.