Audio and video localization present challenges that are very unique to this form of media. Typically, foreign language translations are longer than their English equivalents. For example, Spanish usually expands by 15-20%, while French and German typically expand by 20-25%. In written documentation translation or software localization, this type of word expansion can generally be accommodated by resizing fonts, by filling the white space of the document or adding pages, or by resizing dialogue boxes.

For audio and video localization, the constraint is time rather than written length, which is a much more challenging task to overcome. In challenges such as program length restrictions and lip synchronization, not only is translation required, but transliteration is often employed as well - paraphrasing in such a way that the content remains accurate while still maintaining the same feel as the original message.

Special attention is required in choosing the right people to perform this task. Translators and narrators must be native speakers of the required language and proficient in the ongoing idiomatic changes to both English and their respective languages. The translator needs to be able to creatively design the best approach to the translation in order to convey the meaning of the subject matter as it was originally intended in English. In addition, the narrator's vocal delivery must contain no accent. It should be impossible to hear even regional dialects of a particular country regardless of the language, unless a particular dialect is requested. When the translation is completed, at least two additional translators equally familiar with the particular subject matter should verify and confirm the translation.

All of these criteria are essential for guaranteeing accuracy and professionalism in audio/visual mediums.