What kind of grease is that?
That is old grease with debris in it, this will be shavings of the bearings and their channel.

Before re-greasing the headset you will need to degrease it to remove all of the old grease, otherwise the old grease will attack the new grease rendering it less effective. 
Then once degreased you will then need to clean out all of the degreaser (again so it doesnt attack the new grease) and dry it out. 
Then you can add the new grease, the thicker and gloopier the better