Last week, the broadcaster announced it will deliver live BBC One and BBC Two shows online - with users simply logging onto the designated channel website from any PC, mobile phone or other internet-enabled device.
However, price comparison site BroadbandChoices said those regularly watching live BBC programmes online could exceed the monthly download limits imposed by their ISP.
Michael Phillips, product director of BroadbandChoices, described the BBC's new online service as "a positive step forward" but expressed concern that the public may not be sufficiently aware of their ISPs' broadband usage caps and fair usage policies.
BBC live streaming"The BBC iPlayer successfully opened up the downloading of high quality video programmes from a dedicated minority to the general public and this new service takes things one step further with high quality video streaming," said Phillips.
"As a public service broadcaster they have a responsibility to clearly inform users of the potential impact to their broadband service and punitive charges they might incur through accessing high quantities of this content."