Should I use 'media,' or 'medias?'

Solution 1:

In the rare cases where the word 'media' is not being used as a collective noun (making it unpluralizable) media is the plural of medium and therefore already plural. If you wanted to single out television, for example, as opposed to other media, you would call television 'a medium'.

The phrase you saw is wrong. The correct phrase is:

"... it was a good general point about representation and how some media seem to be handling it."

Or to be more explicit...

"One medium handled the situation well, but other media were less good."

Solution 2:

Dictionary.com puts forward an alternative, less prescriptive view:

Usage note
Media, like data, is the plural form of a word borrowed directly from Latin. The singular, medium, early developed the meaning “an intervening agency, means, or instrument” and was first applied to newspapers two centuries ago. In the 1920s media began to appear as a singular collective noun, sometimes with the plural medias. This singular use is now common in the fields of mass communication and advertising, but it is not frequently found outside them.

However, these Google Ngrams surely indicate that the 'repluralised' form medias is non-standard.