libertarians justify slavery or indentured servitude

libertarians first and foremost believe in non-aggression, voluntary trade. so slavery, in so far as it was forced upon someone via violence or the threat of violence would not be justified.

  If you are coming from the point of view that there is no problem with sweatshops and things don't need to change

None of the video's I linked to, nor it is my position that things do not need to change, your emotional response is the problem, you lack the ability to react with logic, to understand how the world actually works, instead you lash out with emotion about how the world "should" work in your opinion

  How long have China, India, Pakistan, Bangladesh, Vietnam, Malaysia had sweatshops?

They are in reality, why do you think in recent year companies have been flocking back to the US, telecom and tech industries are the most widely known, but many business are coming back. It is the increased in wages in those nations brought about by economic development via sweatshops coupled with the reducing wages in the US brought about by the failed economic policies of the US government