If you want to avoid anything with bias, you better disconnect your router because literally every person is biased one way or another. When viewing documentaries it's important to know that, including BBC ones, so you can have that in mind, not avoid watching the documentaries at all.

Who is unbiased in this case? You have to acknowledge that all parties have agendas.

Apparently martin82's comment was too subtle for you so here it is more explicitly. The BBC has a long history of antisemitic and anti-Israel bias. This is not a secret.