In german they don't use the continous form. You have to use, in that case, simple present with a relative pronoum. Like that: Gestern habe ich geträumt, dass ich einen Film mit meinen Freunden filme.

The reason why you struggle with the German translation might be that your sentence doesn't make much sense - in English. There's no reason to tell this in past continuous unless you dreamt something else happened at the same time. In English you would need to tell this like: Yesterday I dreamt that I filmed a movie with some friends. In German you can tell it as Raphael suggested. There’s no continuous tense in German, that’s correct. However, there are a lot of terms which are used when talking about actions in progress. Which of them are applicable depends on the context.

Sehr gute Frage, Yuli. Viele Deutschlerner haben irgendwann die gleiche Frage gestellt. Ich auch. Deutsch ist "leider" nicht so einfach wie Englisch. Sie können natürlich solche Sachen ausdrücken, aber du solltest einen Deutschen danach fragen. Viele Grüsse!