How to create an if else statement that cycles through a class in the model

How to create an if else statement that cycles through a class in the model

I have a rails app that displays videos. I only want to display videos if
they have a thumbnail, so I have this code in model:
def thumbnail_ready?
BitsOnTheRun::call('videos/thumbnails/show', video_key:
key).thumbnail.status == 'ready' rescue false
end
and this in my view:
<% if video.thumbnail_ready? %>
...
<% end %>
The problem is, when the thumbnail isn't there, nothing is displayed at
all. What I want is for it to check if the thumbnail is available
beforefor it gets to the view - somewhere in the model or controller - and
only ever pull out thumbail_ready? videos. How can I do this? The current
solution doesn't work on arrays.
An alternative would be to keep this solution, but automatically cycle
through to the next video with an available thumbnails. I'm also unsure
how to do this.
Any advice/help gratefully received - thanks!