Washington Post tried to analyze the data and reached a conclusion that Trump was wrong - https://www.washingtonpost.com/news/fact-checker/wp/2015/07/...

American thinker did a meta-analysis and found WaPo to be misleading - http://www.americanthinker.com/articles/2015/07/illegal_alie...

Personally, I am ambivalent precisely due to the difficulty of tracking these statistics. The raw numbers used are public and quoted in both pieces.

Off-topic, that Molyneux video is HD which is incredibly pleasing on the eyes. Thank you for that. :)