Anti-dither is a setting commonly found on DVRs. Anti-dither is the amount of time your security system records having detected motion. For example, if you have set the Anti-Dither setting to ten seconds when your security system detects motion, it will record for ten seconds. If after the ten seconds, another motion is detected, your security system will record it for a further ten seconds.
Your anti-dither setting is important because it will help you manage your storage usage i.e the longer your device records the more storage you will use.
Generally, you can leave this setting at the manufactures default setting which is usually 5-10 seconds. Though some people prefer to have a longer anti-dither between 15-30 seconds to ensure that they have captured the footage they need in the event of a crime or investigation this should only be done if you have adequate storage.