Update - Just released a new version which supports Instagram videos.
This plugin is really simple we are first searching all the links in the page for anything which mentions instagram. Once we have a link we are hitting the JSONP API of Instagram to fetch the image and insert it directly into Tweetdeck.
To install first install the browser extension tampermonkey. Once installed create a new script, copy and paste the code in above. Make sure you enable the script and there you go.