Most users are quick to blame YouTube when videos have difficulty buffering or playing at all, but the service is now offering a new tool to allow users to find out why.

YouTube's new 'Video Quality Report' page displays video playback quality for Internet Service Providers in your area, and measures ISPs based on their ability to stream HD content to customers from its content delivery networks (CDNs).

The page follows a fellow page from Netflix, launching soon in Australia, which has spent the last few months publicly shaming ISPs for slow download speeds.

Google said this is how it judges ISPs:

A typical YouTube video playback consists of a YouTube client (player) fetching video bytes in a streaming fashion from a YouTube server (CDN), in one or more requests (e.g. HTTP GET). The first step in determining ISP ratings is to measure the sustained speed at which these video bytes are transferred from server to the client. To measure the achieved application level throughput (goodput), the following are recorded for each request:

1) Request Identity: The originating request’s timestamp, access network (e.g. network block, autonomous system number of ISP) and the coarse geographical location (e.g. country, metro), derived from client attributes such as IP address, User Agent, etc. Note that the IP to location translation done by our automated systems may return a location that is incorrect for some users.
2) Response Size: The number of application bytes (including application headers but excluding any kernel level overhead) transferred by the server to the client, in response to the request.
3) Response Time: The time taken to service the request by server, including network transmission time (all bytes acknowledged by the receiver).

Based on these measurements, the goodput for a given request ‘R’ is computed using the formula below. Each measured request is considered a goodput sample.

YouTube says it then assigns each ISP a rating - and to achieve an 'HD' rating, an ISP needs to indicate that 90% of connections made are able to sustain a HD (720p and above) stream.

Four Aussie ISPs made the grade - Telstra Cable Broadband, NBN providers SkyMesh and Activ8Me, and Service Elements, a wholesale network provider.

Budget ISPs Beagle Internet and Amnet Broadband ranked poorly, earning 'Lower Definition' rankings. 

Google said it was working on several things to help users get a better experience, including Adaptive Bitrate.

"With Adaptive Bitrate, we break down each video into multiple segments (typically just a few seconds long) for each available video quality," the company said.

"YouTube detects how smoothly a video is playing and adjusts the quality to account for temporary fluctuations in bandwidth or congestion. This can amount to a large number of decisions that must be made in real time to find how to play a single video.

"For example, if you walk away from your Wi-Fi router, the video might switch from 720p down to 480p as the signal becomes weaker."

Check out your ISP results for yourself here.