I don't know if this only happens to me. I noticed the picture quality when it's being casted from mobile app (e.g. from your phone or tablet via Helix TV app) is much lower than watching the same program via Helix TV box. The images (much easier to tell by comparing the fonts from the news program for example) are blur with fussy edges. Another thing I found is that, the picture quality is much better (still lower than the one from the TV box) for the first 1 min (~ 45 seconds actually) then starts to get blurring.
At the beginning I suspected might be due to my Chromecast (internet) connection issues. But on the same device, all other Apps like Netflix, Amazon Prime video are casted crystal clear. Also, I tried on other Chromecast devices, including the newest edition with GoogleTV, and they are also behaving the same.
Speaking of the other casting behavior like from Netflix is that normally the picture quality is lower for the the first minute or so then becomes much clear. It looks like taking sometime to buffer which is understandable. But the Helix casting behavior seems be doing the opposite way.
So wondering have other Helix users seeing the same? Or is this a technical issue, hopefully not a business reason behind this ;-), already known to Videotron?
I don't have an answer to your question unfortunately, but I can say I have the same problem, I'd say quality is 50% worse on casted Helix TV on a Chromecast Ultra than a regular receiver. All other apps are crystal clear