Yes, the internal mic is never a good choice for capturing the speaker output. Before using a screen recording utility to record these news clips, have you considered ways to just download and save the movie files (ie. Video DownloadHelper)? This is not always possible and some sites make it a pain to do so (copyright, etc.) but this is a much better solution than recording movie playback.
QuickTime X does not capture system sound by default. There is a workaround using an audio routing tool (Soundflower).
https://rogueamoeba.com/freebies/soundflower/
There are many tutorials all over the Web for how to configure Soundflower to capture system audio while screen recording with QuickTime X:
http://www.macworld.com/article/1159440/soundflower_capture.html
Good luck. Hope this is helpful.