Tommy Robinson found Guilty on all 3 charges at the Old Bailey, London, UK.
Judge Dame Victoria Sharp said the court found Robinson committed contempt of court in three respects.
Full reasons will be given next week but here are some of her comments today:
She said he breached the reporting restriction imposed on the trial, by livestreaming the video from outside the public entrance to the court and by "aggressively confronting and filming" some of the defendants.
She said the content of the video "gave rise to a substantial risk that the course of justice in that case would be seriously impeded" and the confrontation of the defendants was a direct interference with the course of justice.
She added: "In our judgement, the respondent's conduct in each of those respects amounted to a serious interference with the administration of justice.
"Detailed reasons for this decision will be handed down shortly. A hearing to decide the appropriate penalty will take place on a date to be fixed by the court."
Outside the court, ripples of anger turned into howls of fury and disbelief as the verdict filtered through.
A small number of his supporters marched purposefully towards the front of the court entrance, to barriers sectioning off police from the public, to make their feelings known.
The crowd, as one, then began chanting "shame on you" and pointed at the court.