None of the current answers are valid anymore since IMDB currently uses Accept-Language header to detect the browser language.

In case you need to do it anyway, the workaround will be similar to the X-FORWARDED-FOR header modification, which can be accomplished with one of the most popular extensions:

ModHeader for Chrome:

• Choose the request header Accept-Language and set the value as en-US, or your preferred language ISO code;
• Click the + button in ModHeader while you're on the IMDB page so that the filter ends up being https:\/\/www.imdb.com.

HTTP Header Mangler for Firefox:

• After installing the extension, go to Firefox Add-ons Manager, or type about:addons in the address bar;
• Select HTTP Header Mangler, access the Options tab, and in the text box paste the desired header request override, like in the example below:

https:\/\/www.imdb.com
Accept-Language=en-US

IMDB currently uses Accept-Language header to detect the browser language.

In case you need to do it anyway, the workaround will be similar to the X-FORWARDED-FOR header modification, which can be accomplished with one of the most popular extensions:

ModHeader for Chrome:

• Choose the request header Accept-Language and set the value as en-US, or your preferred language ISO code;
• Click the + button in ModHeader while you're on the IMDB page so that the filter ends up being https:\/\/www.imdb.com.

HTTP Header Mangler for Firefox:

• After installing the extension, go to Firefox Add-ons Manager, or type about:addons in the address bar;
• Select HTTP Header Mangler, access the Options tab, and in the text box paste the desired header request override, like in the example below:

https:\/\/www.imdb.com
Accept-Language=en-US