git clone https://gist.github.com/ishu3101/6fb35afd237e42ef25f9
mv 6fb35afd237e42ef25f9 ConvertTo-Markdown
cd ConvertTo-Markdown
git remote add github https://github.com/ishu3101/ConvertTo-Markdown
git push github master
git remote rename origin gist
git push github master # To github
git push gist master # To gist
This will also push back your changes to the gist and not only the github repo.
Does it work fine with a gist containing images and videos?