When an ISP has bandwidth bursting configured to their customers , many ( if not all ) customers maxing out their accounts for the bandwidth they have purchased will see their video quality get better, then get worse, then get better, then get worse and sometimes see temporarily frozen video ( or suddenly horrible video )
if you configure properly
burst-threshold that does not happen
I will 90-percent disagree with "...
if you configure properly burst-threshold that does not happen ... " for the average customer who is sustaining their maximum bandwidth from the ISP.
I believe all the major video-on-demand providers ( Netflix , Paramont & ... ) all use rate shifting codex's ( in their players ) that attempt to deliver the best possible quality video that can be played without Random Early Detections ( RED ). When there are frequent REDs, the codex will down-shift. When there are no REDs, the codex will up-shift.
If we take a typical customer with 2 or 3 smart TVs that are streaming , all three smart TVs and their codex will attempt to deliver the best video a codex can deliver. When a burst period expires ( suddenly lots of RED, the codex on all 3 smart TVs will have to down-shift. So now the RED is magnified by a factor of 3 which then triggers all three smart TV codex drivers to temporarily shift-down then shift-up then shift-down then shift-up untill RED is at an acceptable level a codex on each smart TV can handle.
I've been able to lab test this, and almost every time , when burst is encountered , the codex starts changing almost as soon as the next video packet-buffer is received.
Bursting effects much more than video codecs , it effects all TCP and UDP streams because of changing RED conditions.
IMO - The best ISP policy is to not use bursting. If the customer wants a faster account , then let the customer purchase a faster account ( and have the ISP actually deliver the customer purchased bandwidth 99.9 percent of the time 24-hours a day ).