I note that the "anti-Ukrainian rallies" do not happen often in Poland, and - from what I know – the celebrities do not take part in them.
The intention of the organizers of the March of the Defenders of Lviv and Przemysl was to commemorate the Polish victims of the Polish-Ukrainian war of 1918-1919. The participants of the ceremony were, among others, nationalist organizations, including the National-Radical Camp (Obóz Narodowo-Radykalny). This is the part of the members of this organization were to fall regrettable cries of the Ukrainian People's House "Death to the Ukrainians" and "Przemysl, Lviv - all Polish".
This incident deserves condemnation.
But this is only a manifestation of the extreme attitude on the part of the extreme organizations. The vast majority of Poles do not have hostile or negative attitude to the Ukrainian people. Ukrainians, who are studying (approx. 30 thousand people) and work (approx. 1 million) in Poland were not met with hostility.
Negative feelings and fears of a large part of the Polish raise while for historical Ukrainian nationalism, the revival took place in Ukraine after the political upheavals of 2004 and 2014 years (incidentally, supported by the Polish state authorities). State cult figures such as Stepan Bandera, Roman Shukhevych, Dmytro Klyachkivsky, Petro Dyachenko et al. - regarded as heroes in Ukraine and in Poland – are unambiguously associated with the genocide in Volyn and Eastern Galicia (1943-1944) - and the presence in the Ukrainian public space symbolism referring to the OUN and UPA elicit negative reactions part of Polish society. Not for the Ukrainian people, but the ideology of Ukrainian nationalism and its modern epigones. Sometimes these reactions manifest themselves as extreme and politically irresponsible.
That's how I look at the incident in Przemysl. It shows that the difficult history can not be swept under the carpet, it will still come back. This difficult history would be closed once and for all removed as an obstacle in the Polish-Ukrainian relations, when the Ukrainian authorities condemn the OUN, UPA and their crimes.
Unfortunately, after the coup on the Maidan Ukraine has chosen the opposite path - the glorification of the OUN and the UPA as a liberation movement. This will cause tension in relations between the Polish and Ukrainian nations, despite the officially declared friendship at the political level (most recently at the meeting of presidents Duda and Poroshenko in Warsaw on December 2).