The Federal Election Commission is specific about how that disclaimer should appear. The written statement must come at the end of the ad, appear for at least four seconds, be readable against a contrasting background and occupy at least 4% of the vertical picture height. The candidate will typically identify themselves and say the message aloud.
If the message was not approved by a candidate, then the spot will typically name the entity that is responsible, usually a political committee, group or person. There’s also usually language about who financed the commercial.