[rupellohn]

The fingerprint is derived from the aggregate size of all packets that comprise a segment of video (what the researchers call an ADU),

Some possible counter-measures are discussed in the conclusion:

"To that end, we believe that Netflix could defend against passive traffic analysis by ensuring that the byte-range portion of the HTTP GETs sent by the browser do not perfectly align with individual video segment boundaries. For instance, the browser could average the size of several consecutive segments and send HTTP GETs for this average size. As an alternative approach, the browser could randomly combine consecutive segments and send HTTP GETs for the combined video data. Designing obfuscation techniques for VBR DASH streams that do not degrade video quality remains a potential area for future research."