lets compare apples to apples, not apples to oranges.
does this issue occur anywhere you use this app or only at one location (like your home?).
the htc one can surely stream audio and video just fine as many others can attest, but when it comes to wifi connections, these are where bottlenecks and issues can crop up.
could be issues on the wifi network you are using. could be that some ports on the wifi network you are using need to be opened.
could be interference with nearby 2.4ghz appliances or other devices causing the issue.
are you on a 2.4 ghz network? if so, is it crowded? do you have a wifi sniffing app that can survey the network to see how robust of a signal you have? just because you have a "strong wifi signal" does not meant anything.
are there other devices using the same wifi network on the same channel? have you tried changing channels? have you rebooted the wifi router you are using? is the router up to date?
have you contacted comcastic and spoken with their tech support? have you been over to their forums to see if other htc one users have this issue?
are you rooted? do you have sufficient memory to run a cup intensive streaming apap such as this?
have you tried other video apps, such as youtube, or wen to any streaming sites such as vimeo to test the capabilities of the htc one and get a reference point on how well it streams on this wifi network you are using?
lots of steps on your end you can do to help. none of us over the internet can really pinpoint the issue because we are not able to look at the phone, survey your network, and offer more help. we can only speculate...
EDIT: looking at the reviews in the store:
seems many others who use other android devices are having some issues with this app, so perhaps we should move this discussion to the android applications sub subforum for other ANDROID device users to comment, as i doubt this is an issue with the htc one.
also, chromecast is fast becoming one of the go to gadgets. i use chromecast and its amazing, and some people are using chrome browser with chromecast to stream