'avid viewer' is correct and usable in written English. You can use it when you want to describe someone who is passionate and enthusiastic about something. For example, "He was an avid viewer of classic films."
I love the concept of the show and have been an avid viewer of both series.
Yet even the most avid viewer eventually needed to break away.
Unusually for an avid viewer and frequent regurgitator of Fox & Friends, Donald Trump did not tweet on the matter.
An avid viewer of television's New Faces, he harboured dreams of becoming Mickie Most, shaggy-permed 'brains' behind Suzi Quatro.
Carlineo appears to have been an avid viewer of Fox News, once mentioning on his Facebook page that he had been told he watched the channel too much.
David Bowie's father, Hayward Jones, who was working on the show at the time, launched the Lenny the Lion Fan Club because his son was an avid viewer.
They certainly are the series' most avid viewers.
The authenticity appeals to television veterans, who say they are avid viewers of The Onion's videos.
The new militant jihadis tend to be users of the web and avid viewers of satellite television.
The most avid viewers are not only older, they also live many time zones away from Moscow and St .Petersburg, without smart phones, sushi or ski vacations in the Alps.
STAMPY CAT iOS/Android - FREE Millions of children are avid viewers of the Minecraft videos of Stampy, aka British YouTuber Joseph Garrett.
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MA of Applied Linguistic, Maquarie University, Australia