Tweetbot for Mac has been updated with large image/video thumbnails to match the recent update to its iOS counterpart. The thumbnail option can be turned off entirely in the display settings, but I’m not sure why you would want to do that because they look great.
The app also supports three finger left/right swipes in the timeline if your Mac’s trackpad is configured that way. Some bugs have been squashed as well, so be sure to get the update in the Mac App Store. Tweetbot costs $20.
Source: Mac App Store.