Reading the tail end of a video address

Everything after the question mark is a list of settings

A web address has two halves. Up to the question mark it names a server and a location on that server. After the question mark it carries extra instructions for whatever is at that location.

Those instructions are called the query string, and they are ordinary text rather than a code. The site at the other end reads the ones it recognises and passes over the rest. Nothing after the question mark is damage, and its length says nothing about whether the address works.

How a query string is put together

The structure is small enough to learn in one reading, and knowing it removes the urge to tidy an address up.

• One question mark opens the query string, and only the first one counts. Later question marks are just characters.
• Each instruction is a name, an equals sign, and a value, in that order.
• An ampersand separates one instruction from the next, so three ampersands mean four instructions.
• Symbols that would confuse the structure are written as a percent sign and two characters, which is why you sometimes see %2F or %3A inside a value.

Which instructions the source reads and which it discards

A single query string frequently mixes two unrelated kinds of instruction. Some describe the video: which item to load, which quality to start at, how many seconds in to begin playing. Others describe the click: which campaign the visitor came from, which newsletter, which app shared it.

The site itself sorts the two. It acts on the names it knows and ignores the names it does not, which is why the same video plays correctly whether it was reached from a search result, an email, or a shared message. Vidzilla passes the address on whole and lets the source do that sorting, exactly as a browser does.

Why trimming a query string by hand breaks downloads

Tracking parameters and video parameters sit in the same string, in no fixed order, and look alike. Both are a short name, an equals sign, and a run of letters and numbers. There is no reliable way to tell them apart by eye.

Deleting from the question mark onwards therefore removes the tracking and, on many sites, the video identifier with it. The shortened address still opens, which is what makes the mistake convincing, and it opens a home page or a section with no single video on it. Analyze then returns an empty list for an address you have made worse. Paste the address as you copied it and let the extra parameters be ignored where they are.

When the parameter is the video

On plenty of sites the address before the question mark is the same for every video on the whole platform, and the query string is the only thing that distinguishes one from another. The path names a player or a viewing page, and a parameter such as v, id, or vid carries the identifier of the individual video.

Those addresses are the reason the advice above is absolute rather than cautious. Strip the query string from one of them and you are left with a page that shows no particular video, so there is nothing for Analyze to read. Recognising the shape is straightforward: if the part before the question mark contains no number, no long code, and no title, the identifier is in the query string and every character of it is load-bearing.

The hash at the very end is not a parameter

Some addresses finish with a hash sign followed by a word or a number. That part is a fragment, and it is handled by the browser rather than sent to the server. It scrolls a page to a heading or opens a particular panel.

A fragment does not identify a video and does not need removing. Leave it attached. If the video only appears once the page has jumped to that panel, the fragment is doing useful work and taking it off costs you the video.

What the query string changes about your file

Nothing. Whatever the parameters ask the source page to do on screen, the file you download is the complete encoding on the row you selected.

A start-time parameter is the clearest example. It tells the player to begin at four minutes, and the file that reaches your device still contains the video from its first frame. Analyze reports each available encoding with a resolution and a size, and the row is the file.

Related pages

• Working from a raw URL out of a document or an embed
• Reading an address to see what it points at
• Addresses that pass through redirects
• Getting the address into the box undamaged